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Earth's Shifting Crust
A Key to Some Basic Problems of Earth Science
by CHARLES H. HAPGOOD
with the collaboration of JAMES H. CAMPBELL
Foreword by
ALBERT EINSTEIN
PANTHEON BOOKS
Copyright © 1958 by Charles H. Hapgood
Published by Pantheon Books Inc.
333 Sixth Avenue, New York 14, N. Y.
Published simultaneously in Canada by
McClelland & Stewart, Ltd., Toronto, Canada
Library of Congress Catalog Card No. 58-5504
Manufactured in the U.S.A.
to FRED, WILLIE, PRU, and MARY G.
TABLE OF CONTENTS
FOREWORD by Albert Einstein j
AUTHOR'S NOTE: To the Layman and the Specialist 3
ACKNOWLEDGMENTS 5
INTRODUCTION: A New Theory 10
i. Some Unsolved Problems, 10; 2. Crust Displacement as
a Solution, 13; 3. A Possible Cause of Crust Displace-
ment, 15
I. PAST THEORIES OF POLAR SHIFT 24
i. Older Theories, 24; 2, The Wegener Theory, 26;
3. New Proposals of Polar Shift, 32
II. THE ICE AGES 34
i. The Failure of the Older Theories, 34; 2. The Mis-
placed Icecaps, 35; 3. World-wide Phases of Cold Weather,
38; 4. The New Evidence of Radiocarbon Dating, 44;
5. The New Evidence from Antarctica, 49; 6. Conclu-
sion, 56
III. ANCIENT CLIMATES 58
i. Ages of Bloom in Antarctica, 58; 2. Warm Ages in the
North, 61; 3. Universal Temperate Climates— A Fallacy,
65; 4. The Eddington-Pauly Suggestion, 70; 5. The Con-
tribution of George W. Bain, 7156. The Contribution of
T. Y. H. Ma, 73; 7. On the Rate of Climatic Change, 77
IV. THE MOUNTAINS 79
Part I. The Folding and Fracturing of the Crust, 79;
i. The Problem of Crustal Folding, 80; 2. Campbell's
Theory of Mountain Building, 90; 3. The Effects of Pole-
ward Displacement, 100; 4. The Mountain-Building
Force, 103; 5. Existing Fracture Systems as Evidence for
the Theory, 104
Part 1L Volcanism and Other Questions, in; 6. Volcan-
ism, 1 1 1 ; 7. The Volcanic Island Arcs, 11418 The Heat of
the Earth, 116; 9. Changing Sea Levels, 120; 10. Some
Light from Mars, 126; n. Undisturbed Sections of the
Crust, 127; 12. The Chronology of Mountain Building,
128
V. CONTINENTS AND OCEAN BASINS 132
i. The Central Problem, 132; 2. The Views of the Geo-
physicists, 134; 3. The Views of the Biologists, 135;
4. Geologists Allied with Biologists, 139; 5. The Evidence
of Oceanography, 145; 6. The Deeper Structure of the
Earth's Crust, 149
VI. THE SHAPE OF THE EARTH 158
i. Isostasy and the Icecap, 158; 2. The Antarctic Icecap Is
Growing, 164; 3. A Suggestion from Einstein, 172; 4. The
Triaxial Shape of the Earth, 180; 5. The State of Matter
Below the Crust, 185
VII. NORTH AMERICA AT THE POLE 193
i. The Polar Icecap, 193; 2. The Displacement Caused by
the Ice Sheet, 197; 3. The Cause of the Oscillations of the
Ice Sheet and the Cause of the Climatic Optimum, 204;
4. The Glaciation of Europe, 2 10; 5. Changes in Sea Level
at the End of the Ice Age, 216; 6. Darwin's Rising Beach-
line in South America, 225
VIII. THE GREAT EXTINCTIONS 227
i. The Extinction of the Mammoths, 227; 2. The Mam-
moth's Adaptation to Cold, 229; 3. The Present Climate
of Siberia, 233; 4. A Sudden Change of Climate?, 237;
5. The Beresovka Mammoth, 244; 6. The Interpretation
of the Report, 249; 7. The Mastodons of New York, 257;
8. StormI, 266
IX. EARLIER DISPLACEMENTS OF THE CRUST 272
i. Introduction, 272; 2. Weakness of the Accepted Glacial
Chronology, 278; 3. The Beginning of the Wisconsin Gla-
ciation, 283; a. The Arctic Cores, 284; b. Earlier Phases
of the Wisconsin Glaciation, 287; 4. Greenland at the
Pole, 288; a. Cores from the San Augustin Plains, 290;
b. Some North Atlantic Cores, 293; c. A North Atlantic
Land Mass?, 297; d. Additional Atlantic Cores, 300;
5. Alaska at the Pole, 303; 6. The Remoter Past, 308
X. LIFE 315
i. The Cause of Evolution, 315; 2. The Problem of Time,
316; 3. Climate and Evolution, 320; 4. The Distribution
of Species, 325; 5. The Periods of Revolutionary Change
in Life Forms, 329; 6. The Extinction of Species, 332;
7. The Gaps in the Fossil Record, 337; 8. Summary, 339
XI. CAMPBELL'S MECHANISM OF DISPLACEMENT 340
i. The Logic of the Evidence, 340; 2. Calculating the
Centrifugal Effect, 343; 3. The Wedge Effect, 345; 4. Some
Difficulties, 352; 5. The Calculations, 359; 6. Notes of a
Conference with Einstein, 361; 7. Isostasy and Centrifugal
Effect, 365
XII. CONCLUSION 379
i. Looking Forward, 379; 2. A General Summary, 386
APPENDIX: Letters from Albert Einstein and George
Sarton 390
GLOSSARY 393
BIBLIOGRAPHY 396
INDEX OF NAMES 421
INDEX OF SUBJECTS 425
LIST OF ILLUSTRATIONS
Fig. I. The Centrifugal Effect of the Antarctic Icecap.
John L. Howard. 18
Fig. II. Mountain Building: Patterns of Fracture and
Folding. James H. Campbell. 94
Fig. III. Vertical View of the Earth with Cross Section at
96° E. Long. James H. Campbell. 95
Fig. IV. Patterns of Fracture. James H. Campbell. 96
Fig. V. Consequences of Displacement: Cross Section of
Earth at 96° East of Greenwich Showing Centrif-
ugal Effect of Icecap. John L. Howard. 154
Fig. VI. Consequences of Displacement: Cross Section of
Earth at 96° East of Greenwich Showing Hypo-
thetical Effect of Shift of Crust. John L.
Howard. 154
Fig. VII. Antarctica: Three Earlier Locations of the
South Pole. John L. Howard. 276
Fig. VIII. Pollen Profile from the San Augustin Plains,
New Mexico. Clisby and Sears. 291
Fig. IX. Chronology of Sediments in the North Atlantic
Cores P-i24(3), P-1«6(5), P-i3o(g). Piggott and
Urry. 295
Fig. X. North Atlantic Cores A 172-6, A 199-4, A 180-
75. Hans E Suess. 301
Fig. XI. Lithology of Core Samples, Ross Sea, Antarctica.
Jack L. Hough. 306
Fig. XII. The Centrifugal Effect of the Icecap. Use of the
Parallelogram of Forces to Calculate the Tan-
gential Component. James H. Campbell. 343
Fig. XIII. A Cross Section of the Earth Showing the Re-
lation Between the Crust and the Equatorial
Bulge. James H. Campbell. 346
Fig. XIV. Various Aspects of the Wedge Effect. James H.
Campbell. 347
Fig. XV. The Wedge Effect. James H. Campbell. 348
"We know that there is no absolute knowledge, that there
are only theories; but we forget this. The better educated
we are, the harder we believe in axioms. I asked Einstein
in Berlin once how he, a trained, drilled, teaching scientist
of the worst sort, a mathematician, physicist, astronomer,
had been able to make his discoveries. 'How did you ever do
it/ I exclaimed, and he, understanding and smiling, gave the
answer:
" 'By challenging an axiom I' "
Lincoln Steffens, Autobiography (p. 816)
FOREWORD by Albert Einstein
I frequently receive communications from people who wish
to consult me concerning their unpublished ideas. It -goes
without saying that these ideas are very seldom possessed of
scientific validity. The very first communication, however,
that I received from Mr. Hapgood electrified me. His idea is
original, of great simplicity, and— if it continues to prove it-
self—of great importance to everything that is related to the
history of the earth's surface.
A great many empirical data indicate that at each point on
the earth's surface that has been carefully studied, many cli-
matic changes have taken place, apparently quite suddenly.
This, according to Hapgood, is explicable if the virtually
rigid outer crust of the earth undergoes, from time to time,
extensive displacement over the viscous, plastic, possibly fluid
inner layers. Such displacements may take place as the conse-
quence of comparatively slight forces exerted on the crust,
derived from the earth's momentum of rotation, which in
turn will tend to alter the axis of rotation of the earth's crust.
In a polar region there is continual deposition of ice, which
is not symmetrically distributed about the pole. The earth's
rotation acts on these unsymmetrically deposited masses, and
produces centrifugal momentum that is transmitted to the
rigid crust of the earth. The constantly increasing centrifugal
momentum produced in this way will, when it has reached a
certain point, produce a movement of the earth's crust over
the rest of the earth's body, and this will displace the polar
regions toward the equator.
Without a doubt the earth's crust is strong enough not to
give way proportionately as the ice is deposited. The only
doubtful assumption is that the earth's crust can be moved
easily enough over the inner layers.
The author has not confined himself to a simple presenta-
2 EARTHS SHIFTING CRUST
tion of this idea. He has also set forth, cautiously and compre-
hensively, the extraordinarily rich material that supports his
displacement theory. I think that this rather astonishing, even
fascinating, idea deserves the serious attention of anyone who
concerns himself with the theory of the earth's development.
To close with an observation that has occurred to me while
writing these lines: If the earth's crust is really so easily dis-
placed over its substratum as this theory requires, then the
rigid masses near the earth's surface must be distributed in
such a way that they give rise to no other considerable centrif-
ugal momentum, which would tend to displace the crust by
centrifugal effect. I think that this deduction might be capa-
ble of verification, at least approximately. This centrifugal
momentum should in any case be smaller than that produced
by the masses of deposited ice.
AUTHOR'S NOTE: To the Layman and the Specialist
This book is addressed primarily to the layman. It is intended
to be read by everyone interested in the earth and in the his-
tory and future of life on the earth.
I believe that the most important problems of science— that
is, the most fundamental principles of scientific thought and
method— may be understood by everyone. I think it is the ob-
ligation of scientists to make these essentials clear, for only in
this way can science arouse public interest. It is unquestion-
able that without a public interest science cannot flourish.
The impression that serious scientific problems are far be-
yond the understanding of the average man constitutes a seri-
ous obstacle to the growth of this public interest. A caste
system of specialists has been created, and it has produced a
sort of intellectual defeatism, so that the layman tends to
think that the conclusions he can reach with his own faculties
are invalid, no matter how carefully he examines the evi-
dence. This is an error that inhibits the spread of scientific
knowledge and tends to discourage the recruitment of scien-
tific workers, for every scientist has been an amateur to start
with.
In addressing this book to the general public, I hope not
only to promote a wider discussion of the basic problems of
the earth; I hope also that from such increased interest will
come more recruits for the study of the earth. This book is
addressed also to the youth of high school and college age,
who, in my opinion, are perfectly capable of reaching sound
conclusions on the evidence set forth in it. From many of
them, in the course of teaching, I have already received not
only an enthusiastic response, but active and practical help.
But this book is necessarily addressed also to the specialists
in the various fields with which it deals. These include geol-
ogy, geophysics, paleontology, and climatology. It is precisely
4 EARTH'S SHIFTING CRUST
here that an attitude discovered among the specialists raises a
serious problem. There is a natural inclination among them
to consider, each one, the evidence falling within his own
field of competence, and that evidence alone. Necessarily, if
the arguments affecting one field alone are considered, and
all the rest are put aside, the weight of probability for the
theory is very greatly reduced, and it becomes easy to con-
clude that, while interesting, it need not be taken very seri-
ously. From this it is but a step to the conclusion that the
theory had better be proved first in one of the other fields:
it will then be soon enough to invest the necessarily consider-
able amount of time, effort, and expense in a restudy of the
basic data affected by the new theory in the specialist's own
field.
So it becomes a question of a scientific passing of the buck:
the paleontologist tends to look to the geologist, the geologist
to the geophysicist, and the geophysicist to the geologist, for
the proof of the theory.
But in the nature of the case, this is a problem for all the
sciences of the earth together. Here the specialists must be-
come general readers, and the general reader must take on
the responsibility of the scientist. By this I mean that the
reader must examine the facts presented here for himself,
and draw his own conclusions without looking to any author-
ity except that of his own reason. If the reader will do that—
and I now include the specialists— I have no fear of the conse-
quences. Either he will accept the theory presented in this
book or he will be inspired to look for a better one.
ACKNOWLEDGMENTS
When it comes time to write an acknowledgment of the assist-
ance received from others in the preparation of a book, this
job is sometimes accomplished in a perfunctory way; it is a
job to be got over with but, at the same time, turned to ad-
vantage. I do not think that this is fair to the essentially social
nature of science. The implication is usually obvious that the
book is, in fact, the work of one or two perspiring and in-
spired persons, who, by themselves alone, have persevered
against odds to complete an imperishable product. This dis-
torts the process by which scientific and, indeed, all original
work is done. Scientific research is essentially and profoundly
social. Discoveries are not the product of single great minds
illuminating the darkness where ordinary people dwell;
rather, the eminent individuals of science have had many
predecessors; they themselves have been merely the final or-
ganizers of materials prepared by others. The raw materials,
the component elements that have made these great achieve-
ments possible, have been contributed by hundreds or thou-
sands of people. Every step in the making of this book has
been the result of contact with other minds. The work done
by hundreds of writers over a number of centuries has been
exploited, and the contributions of contemporary writers
have been carefully examined. The product represents, I
should like to think, a synthesis of thought; at the same time
I hope its original elements will prove valid additions to the
common stock of knowledge in the field.
Credit for the initiation of the research that led to this
book belongs, in the first instance, to students in my classes
at Springfield College, in Springfield, Massachusetts. A ques-
tion asked me by Henry Warrington, a freshman, in 1949,
stimulated me to challenge the accepted view that the earth's
surface has always been subject only to very gradual change,
6 EARTH'S SHIFTING CRUST
and that the poles have always been situated precisely where
they are today. As the inquiry grew, many students made
valuable contributions to it, in research papers. Among these
I may name, in addition to Warrington, William Lammers,
Frank Kenison, Robert van Camp, Walter Dobrolet, and
William Archer.
Our inquiry first took organized form as an investigation
of the ideas of Hugh Auchincloss Brown, and I am deeply
indebted to him for his original sensational suggestion that
icecaps may have frequently capsized the earth, for many sug-
gestions for research that proved to be productive, for his
generosity in sharing all his research data with us, and for his
patience in answering innumerable letters.
In this early stage of our inquiry, when I was in every sense
an amateur in many fields into which the inquiry led me, I
received invaluable assistance from many specialists. These
included several members of the faculty of Springfield Col-
lege, especially Professor Errol Buker, without whose kindly
sympathy our inquiry would have been choked in its infancy.
Assistance with many serious problems was received from
Dr. Harlow Shapley, of the Harvard Observatory, Dr. Dirk
Brouwer, of the Yale Observatory, Dr. G. M. Clemence, of
the Naval Observatory, and a number of distinguished spe-
cialists of the United States Coast and Geodetic Survey.
Our inquiry, in its third year, was involved in a difficulty
that appeared to be insuperable, and from this dilemma it
was rescued by an inspired suggestion made by my old friend
James Hunter Campbell, who thereafter became my constant
associate in the research project, and my collaborator. I must
give credit to him for having taken hold of a project that was
still an amateur inquiry, and transformed it into a solid sci-
entific project.
When Mr. Campbell had developed his ideas far enough to
assure us that the idea we had in mind was essentially sound,
it became feasible to submit the results of our joint efforts to
Albert Einstein, and we found him, from then on, a most
sympathetic and helpful friend. Throughout an extended
ACKNOWLEDGMENTS 7
correspondence, and in personal conference, his observations
either corroborated our findings or pointed out problems
that we should attempt to solve. With regard to our inquiry,
Einstein made an exception to his usual policy, which was to
give his reactions to new ideas submitted to him, but not to
offer his suggestions for their further development. In our
case, with an uncanny sense, he put his finger directly upon
problems that were, or were to be, most baffling to us. We
had the feeling that he deeply understood what we were try-
ing to do, and desired to help us. Our association with him
represented an experience of the spirit as well as of the mind.
In the later stages of our inquiry, many distinguished spe-
cialists and friends helped us with particular problems. Help-
ful suggestions have been contributed by Professor Frank C.
Hibben, of the University of New Mexico, Professor Bridg-
man, of Harvard, Dr. John M. Frankland, of the Bureau of
Standards, the late Dr. George Sarton, Professors Walter
Bucher and Marshall Kay of Columbia University, Dr. John
Scott, Mrs. Mary G. Grand, Mr. Walter Breen, Mr. Stanley
Rowe, Dr. Leo Roberts, Mr. Ralph Barton Perry, Jr., Mrs.
Mary Heaton Vorse, Mr. Heaton Vorse, Mr. Chauncey
Hackett, Mrs. Helen Bishop, and Mrs. A. Hyatt Verrill. To
Dr. Harold Anthony, of the American Museum of Natural
History, our debt is enormous. It was he who afforded Mr.
Campbell and me our first opportunity of discussing our
theories with a group of specialists in the earth sciences, when
he invited us to talk to the Discussion Group of the Museum.
In addition, Dr. Anthony has helpfully criticized parts of the
manuscript, and has helped me to get criticism from other
experts. Captain Charles Mayo, of Provincetown, Massachu-
setts, in many long discussions over the years, has contributed
innumerable valuable suggestions.
One far-sighted scientist without whose generous help this
book in its present form would have been impossible is Dr.
David B. Ericson, of the Lamont Geological Observatory. He
has contributed many vitally important bibliographical sug-
gestions, has corrected numerous technical errors, and has
8 EARTH'S SHIFTING CRUST
provided needed moral support. I am equally indebted to
Professor Barry Commoner, of Washington University, who
not only read the manuscript to suggest improvements of
content and style, but also helped me in the preparation of
special articles for publication in the technical journals. Mr.
Norman A. Jacobs, editor of the Yale Scientific Magazine,
published the first of these articles.
During the last year I have received enormous assistance
from Mr. Ivan T. Sanderson, who, as a biologist, has read the
manuscript with a critical eye for misuse of technical vocabu-
lary and for weaknesses in presentation. I have received in-
valuable help from Professor J. C. Brice, of Washington
University, who has criticized the whole manuscript from a
geological standpoint. I am deeply indebted to my aunt, Mrs.
Norman Hapgood, for the first complete translation from the
Russian of the report of the Imperial Academy of Sciences
on the stomach contents of the Beresovka Mammoth, to Mrs.
Use Politzer for the translation from the German of Ein-
stein's letter of May 3, 1953, and to Mrs. Maely Dufty for
assistance with the translation of his Foreword into English.
To many personal friends, in addition to those mentioned, I
owe thanks for encouragement and for suggestions that often
turned out to have major importance. I am indebted to John
Langley Howard for his assistance with the illustration of
this book, to Mr. Coburn Gilman, my editor, for his innum-
erable constructive suggestions and his understanding spirit,
to Mr. Stanley Abrons for his painstaking work in preparing
the Glossary, and to Mr. Walter Breen for preparing the Index.
In the final typing of the manuscript Miss Eileen Sullivan
has had to encounter and survive difficulties and frustrations
that only she and I can have an idea of. I am very gateful for
her help.
Grateful thanks are extended to all publishers and individ-
uals who have consented to the use of selections or illustra-
tions, and in particular to the following:
Columbia University Press, for quotations from George Gay-
ACKNOWLEDGMENTS 9
lord Simpson, Major Features of Evolution; Thomas Y.
Crowell Co., for a passage from Frank C. Hibben, The Lost
Americans; Dover Publications, Inc., for quotations from
Beno Gutenberg, Internal Constitution of the Earth (paper-
bound, $245); W. H. Freeman 8c Co., for quotations from
Krumbein and Sloss, Stratigraphy and Sedimentation; Alfred
A. Knopf, Inc., for quotations from Hans Cloos, Conversa-
tions With the Earth; N. V. Martinus Nijhoff's Boekhandel
en Uitgeversmaatschappij, The Hague, for quotations from
J. H. F. Umbgrove, The Pulse of the Earth; Prentice-Hall,
Inc., for quotations from R. A. Daly, The Strength and Struc-
ture of the Earth; Science, for quotations from various issues
of this magazine; William Sloane Associates, Inc., for quota-
tions from Thomas R. Henry, The White Continent (Copy-
right 1950 by Thomas R. Henry); University of Chicago
Press, for quotations from various issues of the Journal of
Geology.
Charles H. Hapgood
Keene Teachers College,
October, 1957.
INTRODUCTION: A New Theory
i. Some Unsolved Problems
A few years ago a great scientist, Daly of Harvard, remarked
that geologists seem to know less about the earth than they
thought they knew when he was a young man (100). This was
an extraordinary statement, considering the very detailed
studies that have been carried out in innumerable geological
fields during his lifetime. Thousands of scientists, in all the
countries of the earth, have studied the stratified rocks and
the records of life contained in them; they have studied the
structures of mountains and reconstructed their histories;
they have studied the dynamic forces at work in the earth,
and have extended our insights to an understanding of the
features of the ocean bottoms and the deeper structures
within the earth's crust.
Yet, despite this vast expansion of our detailed knowledge,
many of the essential facts of the earth's development have
escaped us. The late Hans Cloos, in his Conversation with
the Earthy said, ". . . we know only the unimportant things
and the details. Of the great slow strides of the earth's gigantic
history we comprehend hardly anything at all" (85:84).
To begin with, the origin of the earth is itself still a matter
of dispute. Until about thirty years ago it was a generally
accepted theory that it originally condensed out of a hot gas,
and that it has been cooling and contracting ever since. This
was the "nebular theory/' In recent decades difficulties have
piled up in connection with this assumption, and at the pres-
ent time an entirely opposite view is held by many geophysi-
NOTE: Figures referring to specific sources listed in the Bibliography (p.
396) are inserted in parentheses throughout the text. The first number indi-
cates the correspondingly numbered work in the Bibliography, and the num-
ber following a colon indicates the page.
INTRODUCTION 11
cists. The new idea is that the earth may have started as a
small, cold planetesimal. It may have grown simply by attract-
ing to itself many smaller particles, such as meteorites and
meteoritic dust. It may have grown hot as a result of the
internal pressures caused by its increasing mass, and because
of the effects of the radioactivity of many bits of the matter it
picked up on its endless journey through interstellar space.
Even a cursory glance at the current literature on this sub-
ject reveals the formidable character of the challenge it pre-
sents to the old theory and indeed to the whole structure of
geological theory based upon it. Dr. Harold C. Uf ey reaches
the conclusion, from impressive evidence, that the earth must
have been formed at temperatures below the melting points
of silicate rocks (437:112). He quotes the opinion of Bowen
that the earth was formed as a solid (438:110). Gutenberg
refers to the work of several geophysicists who have advanced
similar views (194:191-92). Olivier argued, in 1924, that
meteoric phenomena can be understood only in terms of a
growing earth. He remarked, "The planetesimal hypothesis
is the one to which we are logically led when we attempt to
explain meteoric phenomena" (337:272). Coleman pointed
to evidence that some of the ice ages in remote geological
periods seem to have been colder than those of the more re-
cent past (87:102). Slichter, summarizing the results of a con-
ference of chemists, geologists, and geophysicists devoted to
this subject, said,
... In accordance with recent theories, the earth probably has
grown by the accretion of relatively cool materials which were not
molten at the outset. The chemists strongly favored the cool type of
origin. . . . Our conceptions of the development of the primitive
earth are, to say the least, obscure. It is even uncertain whether the
earth today is cooling or heating at depth, but the odds seem to favor
the hypothesis of a heating earth (395:511-12).
Inasmuch as it seems evident that neither view of the
origin of the earth has been established, the layman is forced
to conclude that the problem of the origin of the earth is
unsolved.
12 EARTH S SHIFTING CRUST
More than twenty-five years ago, the geologist William H.
Hobbs pointed out the consequences of the breakdown of
the nebular theory, so far as geology was concerned:
Far more than is generally supposed, the recent abandonment of
the nebular hypothesis to account for the origin of the universe, must
carry with it a rewriting of our science. This is particularly true of
geology, for all that concerns seismology, volcanology, and the whole
subject of the growth of continents and mountains (2i5:vii-viii).
But not only has there been no rewriting: actually, the
very abandonment of the nebular hypothesis has not yet
penetrated to the consciousness of the public. It is even true
that many geologists, when they are addressing their remarks
to the general public, write as if the cooling of the earth from
an original molten state had never been questioned.
Within the frame of reference of this uncertainty regarding
the earth's beginning, most geologists today unhesitatingly
confess that we do not understand the origin of continents,
ocean basins, mountain chains, or the causes of volcanic ac-
tion. We have never solved the mystery of ice ages in the
tropics, nor the equally strange mystery of the growth of
corals and warm-climate flora in the polar zones. There is a
dispute as to whether the present climatic zones have existed
continuously from the earth's beginning. If so, we cannot
account at all for the greater part of the fossils of plants and
animals of the past that did not live within the limits of the
present zones. If the zones have not continuously existed, no
one has been able to show what factor can have operated to
even out temperatures from pole to pole. When we turn to
the theory of evolution, we find that the unsolved problems
of origin, development, and extinction of species are many
and basic. Everybody agrees that evolution has occurred, but
nobody pretends to know how it happened. Our ideas of the
tempo at which geological change has occurred in the past
have been challenged in the most dramatic fashion by new
evidence produced by techniques of dating based on radio-
active isotopes. These new techniques have served to under-
line and emphasize the bankruptcy of the present theory of
INTRODUCTION 1$
the earth. They have, indeed, created many more problems
than they have solved.
It became obvious to me, as I reviewed these problems, and
went back over the controversies that had marked their con-
sideration, that a sort of common denominator was present.
I examined the original sources, and here I noticed that in
the controversies that have raged among geologists over these
separate questions in the last seventy-five years, somebody
usually tried to explain the particular problem in terms of
changes in the position of the poles. This, I found, was the
common denominator. The authors of such theories, unfor-
tunately, were never able to prove their assumptions. The
opponents of the notion of polar change always managed to
point out fallacies that seemed decisive. At the same time, no
one was able to reconcile all the evidence in the different
fields with the idea that the poles have always been situated
where they are now on the earth's surface.
The theory here presented would solve these problems by
supposing changes in the positions of the poles. Campbell has
suggested that the changes have occurred not by reason of
changes in the position of the earth's axis, but simply through
a sliding of its crust. There is nothing new about this idea.
It has been brought forward repeatedly over the last seventy-
five years, and is advocated today by a number of scientists.
This book brings together, I hope in comprehensible form,
the evidence from many fields that argues for such shifts, evi-
dence in many cases accumulated by others. In addition, it
contains a new element. Campbell's concept of the mecha-
nism by which movements of the earth's crust are accounted
for is completely new, although elements of it have been con-
tributed by others.
2. Crust Displacement as a Solution
To understand what is involved in the idea of a movement,
or displacement, of the entire crust of the earth, certain facts
14 EARTH'S SHIFTING CRUST
about the earth must be understood. The crust is very thin.
Estimates of its thickness range from a minimum of about
twenty to a maximum of about forty miles. The crust is made
of comparatively rigid, crystalline rock, but it is fractured in
many places, and does not have great strength. Immediately
under the crust is a layer that is thought to be extremely
weak, because it is, presumably, too hot to crystallize. More-
over, it is thought that pressure at that depth renders the
rock extremely plastic, so that it will yield easily to pressures.
The rock at that depth is supposed to have high viscosity;
that is, it is fluid but very stiff, as tar may be. It is known that
a viscous material will yield easily to a comparatively slight
pressure exerted over a long period of time, even though it
may act as a solid when subjected to a sudden pressure, such
as an earthquake wave. If a gentle push is exerted horizon-
tally on the earth's crust, to shove it in a given direction, and
if the push is maintained steadily for a long time, it is highly
probable that the crust will be displaced over this plastic and
viscous lower layer. The crust, in this case, will move as a
single unit, the whole crust at the same time. This idea has
nothing whatever to do with the much discussed theory of
drifting continents, according to which the continents drifted
separately, in different directions. The objections to the drift-
ing continent theory will be discussed later.
Let us visualize briefly the consequences of a displacement
of the whole crustal shell of the earth. First, there will be the
changes in latitude. Places on the earth's surface will change
their distances from the equator. Some will be shifted nearer
the equator, and others farther away. Points on opposite sides
of the earth will move in opposite directions. For example, if
New York should be moved 2,000 miles south, the Indian
Ocean, diametrically opposite, would have to be shifted 2,000
miles north. All points on the earth's surface will not move
an equal distance, however. To visualize this, the reader need
only take a globe, mounted on its stand, and set it in rotation.
He will see that while a point on its equator is moving fast,
the points nearest the poles are moving slowly. In a given
INTRODUCTION 15
time, a point near the equator moves much farther than one
near a pole. So, in a displacement of the crust, there is a me-
ridian around the earth that represents the direction of the
movement, and points on this circle will be moved farthest.
Two points go degrees away from this line will represent the
"pivot points'* of the movement. All other points will be dis-
placed proportionally to their distances from this meridian.
Naturally, climatic changes will be more or less proportionate
to changes in latitude, and, because areas on opposite sides
of the globe will be moving in opposite directions, some
areas will be getting colder while others get hotter; some will
be undergoing radical changes of climate, some mild changes
of climate, and some no changes at all.
Along with the climatic changes, there will be many other
consequences of a displacement of the crust. Because of the
slight flattening of the earth, there will be stretching and
compressional effects to crack and fold the crust, possibly
contributing to the formation of mountain ranges. There
will be changes in sea level, and many other consequences. In
this book the potential consequences will be discussed in de-
tail, and evidence presented to show that such displacements
have frequently occurred in the earth's history, and that they
provide an acceptable solution to the problems I have men-
tioned above.1
3. A Possible Cause of Crust Displacement
Some years ago Mr. Hugh Auchincloss Brown, an engineer,
developed a theory that great polar icecaps might shift the
poles by capsizing or careening the earth as a whole. He had a
simple idea, suggested by his engineering experience. This
was the concept of the centrifugal effect that may arise from
i To follow the argument presented in this book, the reader will find it help-
ful to use a globe. A small one will do. A globe is better than flat maps for
the purpose of following the many simultaneous changes involved in a dis-
placement of the crust.
i6 EARTH'S SHIFTING CRUST
the rotation of a body, if the body is not perfectly centered
on its axis of rotation. Everyone has seen examples of the
operation of centrifugal force. The principle can be demon-
strated by the ordinary washing machine. I once put a heavy
rug, all rolled up into a compact ball, into a washing ma-
chine, and of course when the machine was set in motion all
the weight remained on one side of the axle. The rotation
produced a very powerful sidewise heave. The centrifugal
effect was sufficient to rip the bolts up out of what had been
a fine antique floor. Engineers know that the slightest inac-
curacy in the centering of a rapidly rotating mass, such as a
flywheel, can result in shattering the rotating body.
Brown pointed out that a polar icecap is an enormous body
placed on the earth's surface, and not perfectly centered on
the axis of rotation. It must therefore create centrifugal
effects, tending to unbalance the earth. He called attention to
certain facts about Antarctica. Antarctica is a large continent,
about twice the size of the United States. It is almost entirely
covered by ice, and the ice is enormously thick. Antarctica
contains many great mountain chains, some of them compara-
ble to the Alps or the Rocky Mountains, but the ice is so
thick that it reaches the tops of most of them, and sweeps over
them. The ice sheet is thought to average a mile in thickness,
and it may be twice as thick in places. It may contain as much
as 6,000,000 cubic miles of ice. Much of this ice is an extra
weight on the earth's crust because it has accumulated so fast
that there has been insufficient time for the earth's crust to
sink and adapt to it. As we shall see, Brown's surmise that the
Antarctic icecap has developed rapidly, and is growing even
now (rather than retreating), is well supported by much re-
cent evidence.
With respect to the eccentricity of this mass, Brown
pointed out that the earth is known to wobble slightly on its
axis. The wobble amounts to about fifty feet, and the earth
completes one wobble in about fourteen months. This means
that the whole planet, including the icecap, is always off
center by about that amount. Brown thought that this slight
INTRODUCTION 1?
eccentricity would, because of the enormous mass of the ice-
cap, produce a great centrifugal effect tending to unbalance
the globe. He made some mathematical calculations to show
the possible magnitude of the effect. He suggested that, at
some point, the icecap would grow so large that the centrif-
ugal effect would suffice to shatter the crust in the earth's
equatorial bulge, and permit the earth to wobble farther off
center. Then the increasing radius of eccentricity would
cause an increase of the centrifugal effect by arithmetical
progression, until the earth capsized. He likened the earth's
equatorial bulge— its slightly greater diameter through the
equator—to a flywheel, which would be shattered by the cen-
trifugal effect of the icecap.
When I first began to study Brown's ideas, I examined his
two basic assumptions with some care. The first was the as-
sumption of the centrifugal effect of bodies rotating off
center, and that was sound enough. The second was the
assumption that the equatorial bulge acted as a stabilizing
flywheel to keep the earth steady on its axis. The investiga-
tion of this assumption involved long research. I finally found
unequivocal support for Brown's contention in the works of
James Clerk Maxwell and obtained further confirmation of
it in correspondence with Dr. Harlow Shapley, of the Har-
vard Observatory, Dr. Dirk Brouwer, of the Yale Observa-
tory, and Dr. Harold Jeffreys, of Cambridge University,
England.
I now sought to find, if I could, the ratio of the unstabiliz-
ing centrifugal effect of the icecap to the stabilizing effect of
the bulge. It was clear that the force of the icecap would
either have to overcome the total stabilizing centrifugal effect
of the bulge, or it would have to shatter the crust, so that the
earth could start to rotate farther off center, thereby initi-
ating a chain reaction of increasing centrifugal effects.
The first task was to estimate the centrifugal effect of the
icecap. Here I thought that Brown had committed an over-
sight, to the disadvantage of his own theory. He considered
die eccentricity of the icecap to be due to the earth's fifty-foot
i8
EARTH S SHIFTING CRUST
wobble. I saw, on looking at the map, what seemed to me a
much greater eccentricity. It was obvious that the South Pole
was not at all in the center of the continent. This being so,
then the icecap, which covers virtually all the continent,
could not be centered at the pole. It seemed to me that the
90*WEST FROM GREENWICH
96' 90%EAST FROM GREENWICH
Fig. I. The Centrifugal Effect of the Antarctic Icecap
To visualize the centrifugal effect that may be caused by the Antarctic
icecap, the reader should imagine the map of Antarctica actually rotat-
ing. The continent of Antarctica makes one complete rotation every
INTRODUCTION 19
first step must be to locate the geographical center of mass
of the Antarctic icecap, and then to apply the standard for-
mula used in mechanics to determine the centrifugal effect.
I asked my friend, Errol Buker, of the Springfield College
faculty, to locate the geographical center. He and later Mr.
Campbell each separately solved the problem, and obtained
closely similar results. It appeared that the center was be-
tween 300 and 345 miles from the pole, allowing a margin
of error for the uncertainties involved in the present state of
Antarctic exploration. This, of course, involved a centrifugal
effect thousands of times greater than that which could be
derived from Brown's assumptions. On this basis Buker calcu-
lated the centrifugal effect, and the calculation was later re-
vised by Campbell (Chapter XI). The calculation applied to
the present Antarctic icecap only. The ice around the North
Pole could be disregarded because, except for the Greenland
cap, it is merely a thin shell of floating ice. The presence of
the Arctic Ocean prevents any thick accumulation of ice.
twenty-four hours with the rotation of the earth, and this is what causes
the centrifugal effect.
The point at the intersection of the two meridians is the South Pole.
This is one end of the axis on which the earth rotates. The small circle
drawn about this point is shown passing through an off-center point
about five degrees (or 345 miles) from the pole. This point is, so far as
we can now estimate, the geographical center of mass of the icecap,
which does not coincide with the South Pole because of the asymmetric
shape of the continent.
The two larger circles, one drawn about the pole as a center and one
drawn about the icecap's eccentrically located center of mass, are a me-
chanical convention used by engineers to illustrate the centrifugal effects
of off-center rotation. If the map is visualized as rotating, the inner
circle drawn about the pole represents the earth in stable rotation, while
the outer circle, drawn about the center of the icecap, is undergoing
violent eccentric gyration. The eccentricity results in an outward cen-
trifugal "throw" in the direction of the meridian of 96° E. Long. The
two arrows show how the force of the earth's rotation is transformed
into a centrifugal effect at right angles to trie earth's axis, an effect pro-
portional to the weight of the ice and the distance of its center of mass
from the axis.
2O EARTH'S SHIFTING CRUST
The second problem was to measure the stabilizing cen-
trifugal effect of the bulge. Since there was no record of any
work having been done previously on this problem, it was
necessary to work it all out from fundamentals. It involved
difficult physical and mathematical problems. Here I was
extremely fortunate in obtaining the generous co-operation
of several of the distinguished specialists of the United States
Coast and Geodetic Survey. They gave me a calculus with
which Mrs. Whittaker Deininger, of the Smith College fac-
ulty, obtained a quantity for the stabilizing effect of the
bulge.
Now we had two quantities that could be compared with
each other: the centrifugal effect of the icecap, tending to
upset the earth, and the stabilizing effect of the bulge. Unfor-
tunately for the theory as it then stood, it appeared that the
stabilizing effect of the bulge was greater than the eccentric
effect of the icecap by several thousand times.
There is no question that this result, had it come earlier,
would have brought the investigation to an end. But my geo-
logical research had been proceeding actively for more than
two years and had produced such impressive evidence that I
felt much opposed to the complete abandonment of the proj-
ect. I discussed the difficulty that had arisen with my friend
Campbell. It was indeed fortunate that I did so, for the solu-
tion came from him when he suggested that if the icecap did
not have sufficient force to careen the whole planet, it might
have sufficient force to displace the earth's crust over the
underlying layers. As a sequel to this conversation, Mr.
Campbell continued to work, for a number of years, on the
implications of his suggestion. The details of his mechanism
to account for crust displacement are presented in Chapter
XI.
The hypothesis that has emerged as the result of this com-
bination of elements is distinguished by its economy of as-
sumptions. It appealed to Albert Einstein because of its
simplicity. It appeared to him that it might be possible, on
the basis of the simple common denominator of this theory
INTRODUCTION 21
of displacement, to solve the many complex and interrelated
problems of the earth that have so long resisted solution.
The simplicity of the idea may raise the suspicion that it
can hardly be so very new. How can anything so extremely
simple as the application of the formula for calculating cen-
trifugal effects, a formula which appears in every high-school
textbook of physics, to a polar icecap, have been completely
overlooked? This thought occurred to me, but I found to
my surprise that, despite the simplicity of the idea, it was
one that had never been investigated. When I first discussed
it with Professor Bridgman, at Harvard, he had the impres-
sion that it was a good idea; he called it a real problem, but
he said he could not believe that it had never been consid-
ered by science. He suggested that I take it up with Pro-
fessor Daly. I did so, and Professor Daly agreed that it was a
real problem, but assured me that it had never, to his knowl-
edge, been investigated. And so it turned out. I have looked
pretty far through the technical literature and have found no
studies covering it. Dr. George Sarton, the historian of sci-
ence, confirmed this finding when he wrote me that "the
combination of ideas is so new that the history of science has
nothing to contribute to its understanding" (p. 391).
This book has been written with three objectives in mind.
I have sought, in the first place, to establish beyond a reason-
able doubt that numerous displacements of the earth's crust
have occurred. I think that this idea may now be accepted
without too much difficulty, especially in view of much recent
work in the field of terrestrial magnetism. Secondly, I have
tried to describe a mechanism to account for displacements
(this is essentially the work of Mr. Campbell) and to present
evidence showing that this mechanism alone can account for
the facts. My third purpose has been to show that the hy-
pothesis of crust displacement provides an acceptable solu-
tion of many of the problems of the earth.
It is quite natural that at first numerous objections should
be raised to this theory. In our correspondence with special-
ists the principal issues that have come up to raise doubts
22 EARTH'S SHIFTING CRUST
include the following: whether we have properly estimated
the magnitude of the centrifugal effect; whether there is any
layer below the crust weak enough to permit crust displace-
ment; whether the Antarctic icecap is really growing, as the
theory requires, or is in retreat; whether the centrifugal effect
we postulate would not in practice merely cause the icecap to
flow off from the Antarctic continent into the sea, rather than
transmit its push to the crust; whether the thrust of the ice-
cap, if it was transmitted to the crust, would be transmitted to
the crust as a whole, as the theory requires, or would be ab-
sorbed in local readjustments of the crust; whether, if both
the poles happened to fall in water areas, icecaps would not
cease to develop, and thus the whole process of crust displace-
ment be brought to an end; why, if crust displacements have
been frequent in geological history, there are not evidences
of more icecaps in the geological record; why, with that as-
sumption, we find some rock formations that appear to have
been undisturbed since the earliest times. All these objec-
tions, and many more, are fully, and I hope fairly, discussed
in the following chapters. Therefore, if the reader finds him-
self asking questions that do not appear to be answered, I
hope he will have patience. He may find that they are an-
swered in later parts of the book.
INTRODUCTION
TABLE I
The Geological Periods
(After Krumbein and Sloss, 258:15)
ERA
Cenozoic
Mesozoic
Paleozoic
Pre-Cambrian
PERIOD
Quaternary
Tertiary
Cretaceous
Jurassic
(Liassic)
Triassic
(Thaetic)
Permian
Pennsylvanian
(Carboniferous)
Mississippian
Devonian
Silurian
Ordovician
Cambrian
Keweenawan
Huronian
Tamiskamian
Kewatinian
EPOCH
Present
Pleistocene
Pliocene
Miocene
Oligocene
Eocene
(Paleocene)
I : PAST THEORIES OF POLAR SHIFT
/. Older Theories
Of all the questions that have been debated in the sciences o£
the earth, perhaps the most fundamental and the most in-
volved is that of the stability of the poles. This question has
bedevilled science for about a hundred years. Despite every
effort to establish the view that the poles have shifted during
the history of the earth, or to prove that they have not, the
controversy is just as lively today as ever. In fact, discussion
of the issue has become much more active during the last
decade. The new evidence bearing on this question, as we
shall see, now strongly favors the idea of polar shift.
When the term "polar shift" is used, it may have several
meanings. It may mean a change of the position of the earth's
axis, with reference to the stars. Everyone has seen pictures
of the solar system, with the earth, planets, and sun shown in
relationship to one another. The earth is always shown
slightly tipped. Its axis does not run straight up and down at
right angles to the plane of the sun's equator, but slants at
an angle.
Now, there is no doubt but that any change in the position
of this axis would be very important to us. It might mean,
for example, that the South Pole would point directly at the
sun. We would then have one hot pole and one cold pole.
The hot pole would never have any night, and the cold pole
would never have any day. The occurrence of this kind of
polar shift has seldom been supposed, for the reason that no
force capable of shifting the axis has ever been imagined,
other than, possibly, a major interplanetary collision.
A second cause of the shifting of the poles with reference to
points on the earth's surface would be a change in the posi-
tion of the whole planet on its axis, without change of the
PAST THEORIES OF POLAR SHIFT 25
position of the axis. The axis would point in the same direc-
tion—toward the same stars— but by a careening motion of
the planet other points would be brought to the poles. Not
the axis, but the whole planet, would have moved or swivelled
around. This is the sort of change proposed by Brown.
As I have already mentioned, the principal obstacle to a
shift of the earth on its axis lies in the existence of the earth's
equatorial bulge, which acts like the stabilizing rim of a gyro-
scope. The early writers on this question, such as Maxwell
(296) and George H. Darwin (105), all recognized that a
shifting of the planet on its axis to any great extent would re-
quire a force sufficient to overcome the stabilizing effect of
the bulge. But they were unable to see what could give rise
to such a force, and dismissed the idea of a shift of the planet
on its axis as utterly impossible and, in fact, not worth dis-
cussing.
This, however, left the evidence unaccounted for, and such
evidence, from many sources, continued to accumulate. Forti-
fied by their very strong conviction that a shift of the planet
on its axis was impossible, astronomers and geologists in-
sisted that all this evidence, such as fossil corals from the
Arctic Ocean, coal beds and fossil water lilies from Spitz-
bergen, and many other evidences of warm climates in the
vicinity of both the poles, simply must be interpreted in ac-
cordance with the assumption that the poles had never
changed their positions on the face of the earth. This placed
quite a strain upon generations of geologists, but their imagi-
nations were usually equal to the task. They were fertile in
inventing theories to account for warm climates in the polar
zones at the required times, but these theories were never
based on substantial evidence. Moreover, they never ex-
plained more than a small number of the facts, while essen-
tially they conflicted with common sense. We shall have
occasion to return to them again in later chapters, where the
statements I have just made will be fully documented.
The discontent of the biologists and paleontologists, who
were constantly finding fossil fauna and flora in the wrong
s6 EARTH'S SHIFTING CRUST
places, finally boiled over, and resulted in a number of new
theories for polar change. New proposals were .frequently ad-
vanced in the i88o's and iSgo's and later, but they were met
by the unyielding resistance of the highest authorities, basing
themselves on the positions taken by the persons already
mentioned. Moreover, it was easy to show defects and contra-
dictions in these various theories, and to discredit them, one
after another. All the assaults were successfully beaten back,
except one.
2. The Wegener Theory
The exception proved to be the theory of Alfred von We-
gener. The latter was a good scientist, though not a geologist.
He was unwilling to be satisfied with theories that would
account for only a few of the facts. He had a passion for
broad, inclusive principles supported by tangible evidence.
He found quantities of evidence that could not, in his opin-
ion, be reconciled with the present positions of the poles.
Inasmuch as the doctrine of polar permanence (and it was a
doctrine any challenge to which evoked remarkable fury
from recognized authorities) forbade any thought that the
poles themselves had moved, or that the earth had shifted on
its axis, Wegener suggested that the continents had moved.
This would have precisely the same effect, for it would mean
that, at different times, different areas would be found at the
poles. And this was, in effect, a third way to account for shift-
ings of the geographical locations of the poles.
Wegener imagined that the continents, formed of light
granitic and sedimentary rocks, had once composed a single
land mass, but had been split and set in motion, drifting over
a plastic substratum of the continents and oceans. He thought
of this sublayer as really plastic and viscous, rather than
rigid and strong. From a vast amount of fossil evidence of
the plant and animal life of the past, he imagined that he
could reconstruct the actual paths of the continents over
PAST THEORIES OF POLAR SHIFT 2?
long periods of time. He proposed to explain the ice ages by
this theory; he suggested that during the last ice age in the
Northern Hemisphere, Europe and America had lain close
together near the pole but that, since then, they had drifted
apart.
Wegener's theory had great appeal. This was not because
all of the evidence supported it, nor because its mechanics
were very plausible, but because it was the only theory that,
at the time, could make sense of the evidence of the fossil
flora and fauna.
There were a number of weaknesses in the structure of
this theory. One of these was that the evidence from different
areas, for the same geological period, would not produce
agreement as to where the poles were situated at a given time.
Chancy, for example, wrote, "It is amusing to note . . . that
in taking care of their Tertiary forests, certain Europeans
have condemned ours to freezing. . . ." (72:484).
Wegener recognized the seriousness of this difficulty:
Although the grounds for the shifting of the poles (in certain
periods of the earth's history) are so compelling, nevertheless it can-
not be denied that all previous attempts to fix the positions of the
poles continuously throughout the whole geological succession have
always led to self-contradiction, and indeed to contradiction of so gro-
tesque a kind that it is not to be wondered at that the suspicion arises
that the assumption of the shifting of the poles is built on a fallacy
(45°:94-95)-
This difficulty, basic as it was, was by no means the worst.
By various methods the knowledge of the structure of the
earth's crust was extended, and it was finally found that the
rock under the oceans, which Wegener had thought to be
plastic enough for the continents to drift over it, is in fact
very rigid. This means that the continents cannot drift with-
out displacing a layer of rigid rock under the oceans, a layer
thought to be at least twenty miles thick and comparatively
strong. It is therefore impossible for the continents to drift.
Dr. Harold Jeffreys, the noted geophysicist, basing his opin-
ion on the evidence for a rigid and comparatively strong
28 EARTH'S SHIFTING CRUST
ocean floor, said, ". . . There is therefore not the slightest
reason to believe that bodily displacements of continents
through the lithosphere are possible" (238:304; 239:346).
The lithosphere, of course, is the crust. The geophysicist
F. A. Vening Meinesz, according to Umbgrove, conclusively
proved the considerable strength of the crust under the
Pacific (430:70).
One of the arguments most frequently heard in favor of
the Wegener theory is based on the apparent correspondence
in shape between certain continents. It would seem, for ex-
ample, that South America might be fitted together with
Africa, and so on. It is claimed that this is evidence that the
two were once parts of one land mass, which must have
broken in two. It is even claimed that rock formations on
opposite sides of the Atlantic match. However, some years
ago, K. E. Caster and J. C. Mendes, two geologists who de-
sired to prove this theory, spent a vast amount of time in
South America, and travelled about 25,000 miles carrying on
field investigations in order to compare in detail the rock
formations of South America with those of Africa. Their
conclusion was that the rock formations did not prove the
theory. Neither, however, did the evidence they had found
disprove it. They added, "Only time and more facts can
settle the issue" (69:1173). Professor Walter Bucher, former
President of the Geological Society of America, also answered
this particular point. He published a map showing the
United States as it would look if flooded up to 1,000 feet
above the present sea level. The map shows that the eastern
and western sides of the resulting inland sea correspond
(57:459)- Thus, if the sea were there now, it would look as
if the two parts of North America had drifted apart. An alter-
native explanation of such parallel or corresponding features
will be suggested in a later chapter.
Another objection to the Wegener theory is that it assumes
that the sea bottoms are smooth plains. This assumption is
necessary for the theory, for otherwise the continents could
not drift over the ocean basins. As the result of the oceano-
PAST THEORIES OF FOLAR SHIFT 2Q
graphic work of recent years, it has been discovered, in con-
tradiction to this, that there are mountain ranges on the
bottoms of all the oceans, and that some of these ranges are
comparable in size to the greatest mountain ranges on land.
Furthermore, several hundred volcanic mountains have been
discovered spread singly over the ocean floors, many of them
apparently of great age.
The Wegener theory involved the corollary that, as the
continents had drifted very slowly across the smooth ocean
floors, these floors had accumulated sediment to great thick-
nesses. It was thought that this sediment should provide an
unbroken record for the whole period of geological time
since the formation of the oceans. The greatest surprise of
recent oceanographic exploration, however, has been the
discovery that this supposed layer of sediment is nonexistent.
The layer of sediment on the ocean bottom is uneven, in
some places only a few feet or a few inches thick, and is rarely
of great thickness. The matter of submarine sediments will be
discussed more fully in later chapters.
Another startling contradiction to the Wegener theory is
presented by recent data that have drastically changed our
former ideas regarding the date of the last ice age in North
America. We have learned, through the new technique of
radiocarbon dating, that this ice age ended only 10,000 years
ago. In Wegener's time it was considered by geologists that
the ice age came to an end at least 30,000 years ago. Since
Wegener supposed that Europe and North America had been
situated close together and not far from the pole during the
ice age, the new data have the effect of requiring an incredi-
ble rate of continental drift. Three thousand miles of drift
in 10,000 years would amount to about 1,500 feet a year.
Furthermore, movement at something like this rate must
still be going on, for the momentum of a continent in motion
would be tremendous. And what would be the consequence
of a continuing movement at this rate? It would mean that
oceanic charts would have to be revised every few years, and
that shipping companies would have frequently to augment
jo EARTH'S SHIFTING CRUST
their fares, because of the ever-increasing distance between
America and Europe.
To cap the case, Gutenberg has shown that the various
forces that Wegener depended upon to move the continents
are either nonexistent or insufficient (194:209), while another
geophysicist, Lambert, has stated that they amount to only
one millionth of what would be required (64:162).
It is interesting to note that despite the quite overwhelm-
ing character of these objections, attempts are still made to
rehabilitate or rescue the Wegener theory. Daly attempted,
some years ago, to find a better source of energy for moving
the continents (98); Hansen cleverly suggested that the centrif-
ugal effects of icecaps might have moved the continents
(199). A contemporary Soviet plant geographer, while recog-
nizing the objections, nevertheless remarked of the Wegener
theory that "it, nevertheless, constitutes the only plausible
working hypothesis upon which the historical plant geogra-
pher may base his conclusions" (463). As recently as 1950
the British Association for the Advancement of Science di-
vided about equally, by vote, for and against the Wegener
theory (351).
This continuing interest in a theory that contains so many
and such serious difficulties is eloquent confirmation of the
insistent pressure of the evidence in favor of polar shifts. It
seems clear that the only reason for the continuing reluctance
to accept polar shifts is the absence of an acceptable mecha-
nism to account for them. The Wegener theory, despite its
appeal, was never generally accepted by scientists, who have
remained, as a body, until very recently, opposed to any sug-
gestion of polar shifts.
We must briefly consider the results of this impasse. The
failure, over a long period of time, of successive proposals to
account for polar change made it impossible for scientists to
accept the field evidence, and to evaluate it on its merits.
With no acceptable theory to account for changes in the posi-
tions of the poles, it was natural that such changes should
be looked upon as impossible. With each successive failure
PAST THEORIES OF BOLAR SHIFT gl
of a proposed theory, the reigning doctrine of the fixity of
the poles was reinforced. As time passed this doctrine became
deeply ingrained, so that all one needed to do to be labelled
a crank was to suggest the possibility of polar changes.
There have been two principal consequences of this en-
thronement of doctrine. In the first place, the evidence
amassed by those who had been led to attack it was quietly
put aside. A part of the evidence was ingeniously explained
away; most of it was simply ignored. The volumes contain-
ing it slept on the back shelves, or even in the storage rooms,
of the libraries, gathering dust. For several years now I have
been busy taking out and dusting off these old books, drag-
ging the skeletons from the closets, and finding much au-
thentic and incontrovertible evidence that changes of the
geographical locations of the poles have occurred at com-
paratively short intervals during at least the greater part of
the history of the earth.
The other consequence of the reigning dogma was the in-
vention of theories to explain those facts that did not fit and
could not be ignored. One such theory, already alluded to,
was that climates were once virtually uniform from pole to
pole; that there were mild, moist conditions enabling water
lilies and magnolias to bloom in the long night under the
Pole Star. No way of accounting for this was ever supported
by a halfway reasonable display of evidence. Nevertheless,
such was the magic of the dogma of the fixity of the poles
that it was accepted, and is still accepted, by a considerable
section of the scientific world. The sum total of the contra-
dictions in this theory, and in the various theories advanced
to explain ice ages, mountain formation, the history of conti-
nents and ocean basins, or evolutionary theory- will appear,
as we proceed, to be essentially the result of the impasse be-
tween the evidence and the doctrine of the fixity of the poles.
The necessity of reconciling the constantly accumulating
facts in a number of fields with a basic error has produced a
multiplicity of theories which are, in fact, a veritable cloud
castle of conjectures, without substance.
32 EARTH'S SHIFTING CRUST
5. New Proposals of Polar Shift
Since truth cannot be suppressed forever, it was inevitable
that accumulating facts should eventually bring the polar
issue again into the foreground. Gutenberg suggested that
while continents cannot drift, perhaps they can creep (194:
211). The British astronomer Gold postulated that the earth's
wobble on its axis could cause a plastic readjustment of its
mantle sufficient to move the poles 90 degrees in a million
years (176). The French geographer Jacques Blanchard sug-
gested the possibility of extensive polar changes due to more
pronounced wobbling of the earth in the past (38). Ting Ying
H. Ma, of Formosa, raised the idea of a combination of conti-
nental drift with displacement of the outer shells of the
earth (285-290). Bain thought of displacements of the crust
to account for facts of ancient plant geography and fossil soils
and suggested a mechanism to try to account for them (18).
Pauly (342) revived the suggestion made by Eddington (124)
that the earth's crust may have been displaced by the effects of
tidal friction. Kelly and Dachille, in a provocative work on
collision geology entitled Target Earth, offered the hypothesis
of displacements of the earth's crust as the result of collisions
with planetoids (248).
The most important recent contribution to the controversy
has certainly been the evidence produced by geophysicists in-
vestigating terrestrial magnetism. This new evidence is so im-
pressive that it has brought about a reversal of opinion in high
geological quarters on the question of the permanence of the
poles. One of the leading specialists in this field, Dr. J. W.
Graham, has recently remarked:
. . . Within the past couple of years there have appeared a num-
ber of serious papers dealing with the subject of polar wanderings by
which is meant a shift of the geographic features of the earth's surface
with respect to the axis of spin. Classical geophysical treatments of
the type pioneered by Sir George H. Darwin early in this century
have been re-examined in the light of our more recent knowledge of
PAST THEORIES OF POLAR SHIFT gj
the earth and its properties, and the conclusion is reached that,
whereas polar wandering was formerly considered impossible, it now
seems to some, at least, inevitable. These re-examinations were in-
spired by deductions based on the rock magnetism studies of the past
few years (428:86).
In 1954 the results of one of these studies were made pub-
lic by the British scientists Clegg, Almond, and Stubbs. They
found impressive evidence of changed directions of the earth's
magnetic field in past periods and concluded:
Finally, it seems therefore that the most likely explanation of the
observed horizontal direction of magnetization of the sediments
studied is that the whole land mass which now constitutes England
has rotated clockwise through 34° relative to the earth's geographical
axis. . . .
If such a rotation of England occurred, it could have been a local
movement of a part only of the earth's crust, or alternately, the earth's
mantle could have moved as a rigid whole relative to the geographical
poles. The first hypothesis would consider the rotation either as a
purely local movement or as part of a drift of large continental land
masses. The second would adduce pole wandering as the operative
mechanism. . . . (81:596).
Many speculations regarding polar changes are being put
forward at the present time without suggesting any mecha-
nism. Thus, in recent months Soviet scientists writing for the
newspaper Red Star had the North Pole situated at 55° N.
Lat. 60,000,000 years ago, and in the Pacific to the southwest
of Southern California 300,000,000 years ago, while in this
country Munk and Revelle suggested that the South Pole
was once over Africa (315).
Needless to say, none of these concepts has been brought
forward without evidence. The evidence is converging from
many directions, with an effect of the confluence of many
rivers into one mighty torrent. The summary of the evidence
is the business of the following chapters.
II : THE ICE AGES
The evidence for displacements of the earth's crust is, as I
have said, scattered over many parts of the earth, and comes
from several fields of science. No other field, however, fur-
nishes so dramatic a confirmation of it as glacial geology.
Much new evidence has recently become available to supple-
ment the older data relating to ice ages.
/. The Failure of the Older Theories
A little more than a hundred years ago people were aston-
ished at the suggestion that great ice sheets, as much as a
mile thick, had once lain over the temperate lands of North
America and Europe. Many ridiculed the idea, as happens
with new ideas in every age, and sought to discredit the evi-
dence produced in favor of it. Eventually the facts were estab-
lished regarding an ice age in Europe and in North America.
People later accepted the idea of not one but a series of ice
ages. As time went on evidences were found of ice ages on
all the continents, even in the tropics. It was found that ice
sheets had once covered vast areas of tropical India and equa-
torial Africa.
From the beginning, geologists devoted much attention to
the possible cause of such great changes in the climate. One
theory after another was proposed, but, as the information
available gradually increased, each theory in turn was found
to be in conflict with the facts, and as a consequence had to
be discarded. In 1929, Coleman, one of the leading author-
ities on the ice ages, wrote:
Scores of methods of accounting for ice ages have been proposed,
and probably no other geological problem has been so seriously dis-
cussed, not only by glaciologists, but by meteorologists and biologists;
THEICEAGES 35
yet no theory is generally accepted. The opinions of those who have
written on the subject are hopelessly in contradiction with one
another, and good authorities are arrayed on opposite . sides. . . .
(87:246).
Recent writers, such as Daly (98:257), Umbgrove (429:285),
and Gutenberg (194:205), agree that the situation described
by Coleman is essentially unchanged. In January, 1953, Pro-
fessor J. K. Charlesworth, of Queen's University, Belfast,
expressed the opinion that
The cause of all these changes, one of the greatest riddles in geolog-
ical history, remains unsolved; despite the endeavors of generations of
astronomers, biologists, geologists, meteorologists and physicists, it
still eludes us (75:3).
A volume on climatic change, edited by Dr. Harlow
Shapley (375), while introducing minor refinements in var-
ious theories, in no way modifies the general effect, which is
that down to the present time the theorizing about the causes
of ice ages has led nowhere.
2. The Misplaced Icecaps
One problem that writers on the ice ages have attempted to
solve, sometimes in rather fantastic ways, but without suc-
cess, is that of the wrong location of the great icecaps of the
past. These icecaps have refused to have anything to do with
the polar areas of the present day, except in a quite inci-
dental fashion.
Originally it was thought that in glacial periods the ice-
caps would fan out from the poles, but then it appeared that
none of them did so, except the ones that have existed in
Antarctica. Coleman drew attention to the essential facts, as
follows:
In early times it was supposed that during the glacial period a vast
ice cap radiated from the North Pole, extending varying distances
southward over seas and continents. It was presently found, however,
that some northern countries were never covered by ice, and that in
j6 EARTH'S SHIFTING CRUST
reality there were several more or less distinct ice sheets starting from
local centers, and expanding in all directions, north as well as east
and west and south. It was found, too, that these ice sheets were dis-
tributed in what seemed a capricious manner. Siberia, now including
some of the coldest parts of the world, was not covered, and the same
was true of most of Alaska, and the Yukon Territory in Canada;
while northern Europe, with its relatively mild climate, was buried
under ice as far south as London and Berlin; and most of Canada
and the United States were covered, the ice reaching as far south as
Cincinnati in the Mississippi Valley (87:7-9).
With regard to an earlier age (the Permo-Carboniferous),
Coleman emphasized that the locations of the icecaps were
even further out of line:
Unless the continents have shifted their positions since that time,
the Permo-Carboniferous glaciation occurred chiefly in what is now
the southern temperate zone, and did not reach the arctic regions at
all (87:90).
He is much upset by the fact that this ice age apparently did
not affect Europe:
Unless European geologists have overlooked evidence of glaciation
at the end of the Carboniferous or at the beginning of the Permian,
the continent escaped the worst of the glaciation that had such over-
whelming effects on other parts of the world. A reason for this exemp-
tion is not easily found (87:96).
One of the most extraordinary cases is that of the great ice
sheet that covered most of India in this period. Geologists are
able to tell from a careful study of the glacial evidences in
what direction an ice sheet moved, and in this case the ice
sheet moved northward from an ice center in southern India
for a distance of 1,100 miles. Coleman comments on this as
follows:
Now, an ice sheet on level ground, as it seems to have been in
India, must necessarily extend in all directions, since it is not the
slope of the surface it rests on that sets it in motion, but the thickness
of the ice towards the central parts. . . .
The Indian ice sheet should push southward as well as northward.
Did it really push as far to the south of Lat. 17° as to the north? It
THEICEAGES 37
extended 1100 miles to the Salt Range in the north. If it extended the
same distance to the south it would reach the equator (87:110-11).
The great South African geologist A. L. du Toit pointed
out that the icecaps of all geological periods in the Southern
Hemisphere were eccentric as regards the South Pole, just
as the Pleistocene icecaps were eccentric with regard to the
North Pole (87:262). Isn't it extraordinary that the Antarctic
icecap, which we can actually see because it now exists, is the
only one of all these icecaps that is found in the polar zone,
where it ought to be?
Dr. George W. Bain, a contemporary writer to whom I
shall refer again, has pointed out a very interesting feature
of the great icecap that existed in the Permo-Carboniferous
Period right in the center of tropical Africa— in the Congo.
He has observed that the icecap, apparently, was asymmetric
in shape: it spread from its center of origin much farther in
one direction than in another (18:46). This is reconcilable
with our theory, which depends upon the asymmetry of ice-
caps. It seems that this African ice sheet reached the present
equator.
Coleman, who did a great deal of field work in Africa and
India, studying the evidences of the ice ages there, writes in-
terestingly of his experiences in finding the signs of intense
cold in areas where he had to toil in the blazing heat of the
tropical sun:
On a hot evening in early winter two and a half degrees within the
torrid zone amid tropical surroundings it was very hard to imagine
the region as covered for thousands of years with thousands of feet
of ice. The contrast of the present with the past was astounding, and
it was easy to see why some of the early geologists fought so long
against the idea of glaciation in India at the end of the Carboniferous
(87:108).
Some hours of scrambling and hammering under the intense
African sun, in lat. 27° 5', without a drop of water, while collecting
striated stones and a slab of polished floor of slate, provided a most
impressive contrast between the present and the past, for though
August 27th is still early Spring, the heat is fully equal to that of a
38 EARTH'S SHIFTING CRUST
sunny August day in North America. The dry, wilting glare and
perspiration made the thought of an ice sheet thousands of feet thick
at that very spot most incredible, but most alluring (87:124).
When these facts were established, geologists sought to ex-
plain them by assuming that, at periods when these areas
were glaciated, they were elevated much higher above sea
level than they are now. Theoretically, even an area near
the equator, if elevated several miles above sea level, would
be cold enough for an ice sheet. What made the theory plausi-
ble was the well-known fact that the elevations of all the
lands of the globe have changed repeatedly and drastically
during the course of geological history. Unfortunately for
those who tried to explain the misplaced icecaps in this way,
however, Coleman showed that they reached sea level, within
the tropics, on three continents: Asia, Africa, and Australia
(87:129, 134, 140, 168, 183). At the same time, W. J. Hum-
phreys, in his examination of the meteorological factors of
glaciation, made the point that high elevation means less
moisture in the air, as well as lowered temperature, and is
therefore unfavorable for the accumulation of great icecaps
(232:612-13).
5. World-wide Phases of Cold Weather
A widely accepted assumption with which contemporary
geologists approach the question of ice ages is that the latter
occurred as the result of a lowering of the average tempera-
ture of the whole surface of the earth at the same time. This
assumption has forced them to look for a cause of glacial
periods only in such possible factors as could operate to cool
the whole surface of the earth at once. It has also compelled
them to maintain the view that glacial periods have always
been simultaneous in the Northern and Southern Hemi-
spheres.
It is remarkable that this assumption has been maintained
over a long period of time despite the fact that it is in sharp
THEICEAGES 39
conflict with basic principles of physics in the field of meteor-
ology. The basic conflict was brought to the attention of
science at least seventy years ago; it has never been resolved.
It consists essentially of the fact that glacial periods were
periods of heavier rainfall in areas outside the regions of the
ice sheets, so that this, together with the deep accumulations
of ice in the great ice sheets, must have involved a higher
average rate of precipitation during ice ages. There is a great
deal of geological evidence in support of this. Only recently,
for example, Davies has discussed the so-called "pluvial"
periods in Africa, and has correlated them with the Pleisto-
cene glacial periods (107).
Now, meteorologists point out that if precipitation is to be
increased, there has to be a greater supply of moisture in the
air. The only possible way of increasing the amount of
moisture in the air is to raise the temperature of the air.
It would seem, therefore, that to get an ice age one would
have to raise, rather than lower, the average temperature.
This essential fact of physics was pointed out as long ago as
1892 by Sir Robert Ball, who quoted an earlier remark by
Tyndall:
. . . Professor Tyndall has remarked that the heat that would be
required to evaporate enough water to form a glacier would be suffi-
cient to fuse and transform into glowing molten liquid a stream of
cast iron five times as heavy as the glacier itself (20:108).
William Lee Stokes has again called attention to this un-
solved problem in his recent article entitled "Another Look
at the Ice Age":
Lowering temperatures and increased precipitation are considered
to have existed side by side on a world-wide scale and over a long
period in apparent defiance of sound climatological theory. Among
the many quotations that could be cited reflecting the need for a
more comprehensive explanation of this difficulty the following seems
typical.
"In the Arequipa region [of Peru], as in many others in both hemi-
spheres where Pleistocene conditions have been studied, this period
appears to have been characterized by increased precipitation as well
40 EARTH'S SHIFTING CRUST
as lowered temperatures. If, however, precipitation was then greater
over certain areas of the earth's surface than it is at present, a corol-
lary seems to be implied that over other large areas evaporation was
greater than normal to supply increased precipitation, and hence in
these latter areas the climate was warmer than normal. This seems at
first to be an astonishing conclusion. . . . We might propose the
hypothesis that climatic conditions were far from steady in any one
area, but were subject to large shifts, and that intervals of ameliorated
conditions in some regions coincided with increased severity in others.
The Pleistocene, then, may have been a period of sharper contrasts
of climate and of shifting climates rather than a period of greater
cold" (405:815-16).
From a number of points of view, the foregoing passage is
extremely remarkable. Stokes recognizes the fact that the
basic assumption of contemporary geologists regarding the
glacial periods is in conflict with the laws of physics. Then, in
the passage he quotes, he draws attention to the implications,
which seem to point directly to crust displacement, for in
what other way can we explain how one part of the earth's
surface was colder and another, at the same time, warmer
than at present?
One of the arguments that is advanced in support of the
assumption of world-wide periods of colder weather (which
remains the generally accepted assumption of glaciologists)
has its basis in geological evidence purporting to prove that
ice ages occurred simultaneously in both hemispheres. A
decade ago, however, Kroeber pointed to the essential weak-
ness of this geological evidence, when he showed the difficulty
of correlating stratified deposits of different areas with each
other:
. . . There is plenty of geologic evidence, in many parts of the
earth, of changes of climates, especially between wet and dry areas;
and some of these happened in the Pleistocene. But the correlation of
such changes as they occurred in widely separated regions, and espe-
cially as between permanently ice-free and glaciated areas, is an intri-
cate, tricky, and highly technical matter, on which the anthropological
student must take the word of geologists and climatologists, and these
are by no means in agreement. They may be reasonably sure of one
series of climatic successions in one region, and of another in a second
THE ICE AGES 41
or third region; but there may be little direct evidence on the corre-
spondence of the several series of regional stages, the identification of
which then remains speculative (257:650).
At the time that Kroeber remarked on the difficulty of
correlating climatic changes in different parts of the world,
we were not yet in possession of the data recently provided by
the new techniques of radiocarbon and ionium dating, which
will be discussed below. The effect of the new data has been
to shorten very greatly our estimate of the duration of the
last North American ice age. This estimate has been reduced,
in the last few years, from about 150,000 years to about
25,000 years, or by five sixths. Now, if we adopt the view that
ancient glaciations, of which we know little, may reasonably
be considered to have been the results of the same causes
that brought about the North American ice age, then we
must grant that they, too, were of short duration. But if this
is true, how is it possible to establish the fact that they were
contemporary in the two hemispheres? A geological period
has a duration of millions of years. An ice age in Europe and
one in Australia might both be, for example, of Eocene age,
but the Eocene Epoch is estimated to have lasted about 15,-
000,000 years. We can discriminate roughly between strata
dating from the early, middle, or late Eocene, but we have no
way of pinpointing the date of any event in the Eocene. Even
with the new techniques of radiodating now being applied
to the older rocks, it is possible to determine dates only to
within a margin of error of about a million years. How, then,
is it possible to determine that an ice sheet in one hemisphere
was really contemporary with an ice sheet or an ice age in
the other?
The attempt to maintain the assumption of the simultane-
ousness of glaciations for the older geological periods is mani-
festly absurd. I shall show in what follows that it is equally
absurd for the recent geological time. It is my impression
that the material evidence for the assumption was never im-
pressive, and that the assumption was never derived em-
pirically from the evidence but was borrowed a priori from
4* EARTH'S SHIFTING CRUST
the parent assumption, that is, the assumption of the lower-
ing of global temperatures during ice ages, which assumption
is, as already pointed out, in conflict with the laws of physics.
If it is true that the fundamental assumption underlying
most of the theories produced to explain ice ages is in error,
we should expect that these theories, despite their many
differences, would have a common quality of futility, and so
it turns out. It is interesting to list the kinds of hypothetical
causes that have been suggested to explain ice ages on the
assumption of a world-wide lowering of temperature. They
are as follows:
a. Variations in the quantity of particle emission and of
the radiant heat given off by the sun.
b. Interception of part of the sun's radiation by clouds
of interstellar gas or dust.
c. Variations in the heat of space; that is, the temperature
of particles floating in space which, entering the earth's
atmosphere, might affect its temperature.
d. Variations in the quantities of dust particles in the at-
mosphere, from volcanic eruptions or other causes, or
variations in proportion of carbon dioxide in the at-
mosphere.
The objections to these suggestions are all very cogent. So
far as the variation of the sun's radiation is concerned, it is
known that it varies slightly over short periods, but there is
no evidence that it has ever varied enough, or for a long
enough time, to cause an ice age. Evidence for the second and
third suggestions is entirely lacking. The fourth suggestion is
deprived of value because, on the one hand, no causes can
be suggested for long-term changes in the number of erup-
tions or in the atmospheric proportion of carbon dioxide,
and, on the other, there is insufficient evidence to show that
the changes ever occurred.
I should make one reservation with regard to the fourth
suggestion. There is one event that would provide an ade-
quate cause for an increase in the atmosphere of both vol-
THE ICE AGES 43
canic dust and carbon dioxide, and that is a displacement of
the crust. The extremely far-reaching consequences of a dis-
placement of the crust with respect to atmospheric condi-
tions, and the importance of the atmospheric effects of a
displacement for other questions, will be discussed in Chap-
ters VII and VIII.
The theories listed above were attacked by Coleman, who
complained that they were entirely intangible and unprov-
able. He said:
Such vague and accidental causes for climatic change should be
appealed to only as a last resort unless positive proof some time be-
comes available showing that an event of the kind actually took
place (87:282).
Another group of theories attempts to explain ice ages as
the results of changes in the positions of the earth and the
sun* These are of two kinds: changes in the distance between
the earth and the sun at particular times because of changes
in the shape of the earth's orbit, and changes in the angle of
inclination of the earth's axis, which occur regularly as the
result of precession. The argument that precession was the
cause of ice ages was advanced by Drayson in the last century
(117). The argument based on these astronomical changes
has been brought up to date in the recent work of Brouwer
and Van Woerkom (375: 147-58) and Emiliani (132). It now
seems that these astronomical changes may produce cyclical
changes in the distribution of the sun's heat, and perhaps in
the amount of the sun's heat retained by the earth, but it is
agreed, by Emiliani and others, that by itself the insolation
curve or net temperature difference would not be sufficient
to cause an ice age without the operation of other factors,
and so Emiliani suggests that perhaps changes in elevation
coinciding with the cool phases of the insolation curve may
have caused the Pleistocene ice ages. One weakness of this
suggestion is, of course, the necessity to suppose two inde-
pendent causes for ice ages.
There is another objection to be advanced against all
44 EARTH'S SHIFTING CRUST
theories supposing a general fall of world temperatures during
the ice ages. We have seen that ice ages existed in the tropics
and that great icecaps covered vast areas on and near the
equator. This happened not once, but several times. The
question is, if the temperature of the whole earth fell enough
to permit ice sheets a mile thick to develop on the equator,
just where did the fauna and flora go for refuge? How did
they survive? How did the reef corals, which require a mini-
mum sea- water temperature of 68° F. throughout the year,
manage to survive? We know that the reef corals, for ex-
ample, existed long before the period of the tropical ice
sheets. Furthermore, we know that the great forests of the
Carboniferous Period, which gave us most of our coal, lived
both earlier than and contemporarily with the glaciations of
Africa and India, though in different places. Obviously, this
would have been impossible if the temperature of the whole
earth had been simultaneously reduced, for the equatorial
zone itself would have been uninhabitable while all other
areas were still colder. It is small wonder that W. B. Wright
insisted, over a quarter of a century ago, that the Permo-
Carboniferous ice sheets in Africa and India were proof of a
shift of the poles (461).
4. The New Evidence of Radiocarbon Dating
The problem of the causes of ice ages has been still further
complicated by a recent revolution in our methods of dating
geological events. In the course of the last ten years all of
our ideas regarding the dating of the recent ice ages, their
durations, and the speed of growth and disappearance of the
great ice sheets have been transformed. This is altogether the
most important new development in the sciences of the earth.
The repercussions in many directions are most remarkable.
In order to get an idea of the extent of the change, let us
see what the situation was only ten years ago. As everybody is
aware, geologists are used to thinking in terms of millions of
THEICEAGES 45
years. To a geologist a period of 1,000,000 years has come
to mean almost nothing at all. He is actually used to thinking
that events that took place somewhere within the same 20,-
000,000-year period were roughly contemporaneous. As to
the ice ages, the older ones were simply thrown into one of
these long geological periods, but there was no way to de-
termine their durations (except very roughly), their speeds
of development, or precisely when they happened. It was
convenient to assume that they had endured for hundreds of
thousands or for millions of years, though no real evidence
of this existed. A good instance is that of the Antarctic ice-
cap, of which we shall hear more below.
So far as the most recent division of geologic time, the
Pleistocene, was concerned, geologists, with much more evi-
dence to work from, saw that there had been at least four ice
ages in a period of about 1,000,000 years. They consequently
proposed the idea that the Pleistocene was not at all like
previous periods. It was exceptional, because it had so many
ice ages. They may have been misled by failure to take suffi-
cient account of the fact that glacial evidence is very easily
destroyed, and that, as we go further back into geological
history, the mathematical chances of finding evidences of
glaciation, never very good, decrease by geometrical progres-
sion.
Down to ten years ago— and, indeed, until 1951 —it was the
considered judgment of geologists that the last ice age in
North America, which they refer to as the Wisconsin glacia-
tion, began about 150,000 years ago, and ended about 30,000
years ago.
This opinion appeared to be based upon strong evidence.
The estimates of the date of the end of the ice age were sup-
ported by the careful counting of clay varves (6) and by
numerous seemingly reliable estimates of the age of Niagara
Falls. As a consequence, experts were contemptuous of all
those who, for one reason or another, attempted to argue that
the ice age was more recent. One of these was Drayson, whose
theory called for a very recent ice age. His followers produced
46 EARTH'S SHIFTING CRUST
much evidence, but it was ignored. When the Swedish scien*
tist Gerard de Geer established by clay varve counting that
the ice sheet was withdrawing from Sweden as recently as
13,000 years ago, the implications were not really accepted,
nor were his results popularly known. Books continued to ap-
pear, even thirty years afterwards, with the original estimates
of the age of the icecap.
Then, following World War II, nuclear physics made pos-
sible the development of new techniques for dating geolog-
ical events. One of these was radiocarbon dating.
The method of radiocarbon dating was developed by
Willard F. Libby, nuclear physicist of the University of Chi-
cago, now a member of the United States Atomic Energy
Commission. It uses an isotope of carbon (Carbon 14) which
has a "half-life" of about 5,568 years (115:75). A "half-life"
is the period during which a radioactive substance loses half
its mass by radiation. Among the very numerous artificial
radioactive elements created in nuclear explosions some have
half-lives of millionths of seconds; others, occurring in na-
ture, have half-lives of millions of years. For geological dating
it is necessary to have radioactive elements that diminish sig-
nificantly during the periods that have to be studied, and
that occur in nature.
Since radiocarbon exists in nature, and has a relatively
short half-life, the quantity of it in any substance containing
organic carbon will decline perceptibly in periods of a few
centuries. By finding out how much carbon was contained
originally in the specimen and then measuring what still re-
mains, the date can be found to within a small margin of
error.
When this method was first developed by Libby, it could
date anything containing carbon of organic origin back to
about 20,000 years ago. Since then the method has been im-
proved, through the efforts of many scientists, and its range
has been nearly doubled.
The first major result of the radiocarbon method was the
THEICEAGES 47
revelation that the last North American ice sheet had indeed
disappeared at a very recent date. Tests made in 1951 showed
that it was still advancing in Wisconsin as recently as 11,000
years ago (272:105); later tests indicated that the maximum
of the ice advance may have been a thousand years later than
that. When these dates are compared with other dates show-
ing the establishment of a climate like the present one in
North America, it seems that most of the retreat and disap-
pearance of the great continental icecap (with its 4,000,000
square miles of ice) can have taken little more than two or
three thousand years.
What is the significance of this new discovery, besides
showing how wrong the geologists had been before? The fact
is that so sudden a disappearance of a continental icecap
raises fundamental questions. It endangers some basic as-
sumptions of geological science. What has become of those
gradually acting forces that were supposed to govern glacia-
tion as well as all other geological processes? What factor can
account for this astonishing rate of change? It seems self-
evident that no astronomical change and no subcrustal
change deep in the earth can occur at that rate.
When this discovery was made, I expected that the next
revelation must be to the effect that the Wisconsin ice sheet
had had its origin at a much more recent time than was sus-
pected, and that the whole length of the glacial period was
but a fraction of the former estimates. I had a while to wait,
because radiocarbon dating in 1951 was not able to answer
the question. By 1954, however, the technique had been im-
proved so that it could determine dates as far back as 30,000
years ago. Many datings of the earlier phases of the Wisconsin
glaciation were made, and Horberg, who assembled them,
reached the conclusion that the icecap, instead of being 150,-
ooo years old, had appeared in Ohio only 25,000 years ago
(222:278-86). This conclusion has been so great a shock to
contemporary geology that some writers have sought to evade
the clear implications, by questioning the radiocarbon meth-
48 EARTH'S SHIFTING CRUST
od. Horberg betrays evidence of the intensity of the shock
to accepted beliefs when he says that the results of the evi-
dence are so appalling from the standpoint of accepted theory
that it may be necessary either to abandon the concept of
gradual change in geology or to question the radiocarbon
method.
In this book I am not going to question the general re-
liability of the radiocarbon method. I intend merely to ques-
tion the theories with which the new evidence conflicts. Dr.
Horberg says that the necessity to compress all the known
stages of the Wisconsin glaciation into the incredibly short
period of barely 15,000 or 20,000 years involves an accel-
eration of geological processes— snowfall, rainfall, erosion,
sedimentation, and melting— that seems to challenge the prin-
ciple laid down by the founder of modern geology, Sir
Charles Lyell, over a century ago. Lyell's principle, called
"uniformitarianism," was that geological processes have al-
ways gone on about as they are going on now.
The Wisconsin icecap went through a number of oscilla-
tions, warm periods of ice recession alternating with cold
periods of ice readvance. Horberg is at a loss to see what
could cause them to occur at the velocity required by the
radiocarbon dates. Allowing for extra time for ice growth be-
fore the evidence of massive glaciation in Ohio 25,000 years
ago, Horberg manages to expand this 15,000 years to 25,000
for the duration of the glacier, but this does not solve his
problem. Even so, the radiocarbon dates seem to require an
annual movement of the ice front of 2,005 feet, "two to nine
times greater than the rate indicated by varves and annual
moraines" (222:283).
The fact that these new facts call into question some basic
ideas in geology is recognized by Horberg:
Probably only time and the progress of future studies can tell
whether we cling too tenaciously to the uniformitarian principle in
our unwillingness to accept fully the rapid glacier fluctuations evi-
denced by radiocarbon dating (222:285).
THEICEAGES 49
Recent geological literature shows that a rather desperate
effort is being made to blur the significance of the new data.
We will return to this question later. Here I would like to
suggest some far-reaching implications of these facts. We have
seen an ice sheet appear and disappear in—geologically speak-
ing—a twinkling of an eye. There are three deductions to be
made:
a. Any theory of ice ages must give a cause that can operate
so fast.
b. If the last icecap in North America appeared and disap-
peared in 25,000 years, we cannot assume that the an-
cient icecaps lasted for longer periods.
c. If other geological processes are correlated with ice ages,
then their tempo must also have been faster than we
have supposed, and a cause must be found for their
accelerated tempo.
In later chapters we shall see that a displacement of the
crust must accelerate these geological processes.
5. The New Evidence from Antarctica
Another kind of radioelement dating has provided us with
new data as revolutionary in their implications as the data
produced by the radiocarbon method. This is referred to as
the radioelement inequilibrium method or (for short) the
ionium method of dating. It was developed by Dr. W. D.
Urry and Dr. C. S. Piggott, of the Carnegie Institution of
Washington, before World War II (439, 440). In recent years
it has been widely applied in oceanographic research by both
American and foreign scientists.
The ionium method is used with sea sediments. It is based
upon three radioactive elements, uranium, ionium, and
radium, which are found in sea water and in sea sediments,
and that decay at different rates. As the result of the different
50 EARTH'S SHIFTING CRUST
rates of decay, the proportions of the three elements in a
sample of sediment change with time, and thus it is possible,
by measuring the remnant quantities of the three elements,
to date the samples.The samples are obtained by taking long
cores from the bottom of the sea. A core is obtained by lower-
ing a coring tube from a ship. It pierces the bottom sediments
and obtains a cross section of them. The ionium method per-
mits dating back as far as about 300,000 years.
Among the materials first dated by Urry's method were
some long cores that had been taken from the bottom of the
Ross Sea in Antarctica by Dr. Jack Hough during the Byrd
expedition of 1947-48. These cores showed alternations in
types of sediment. There was coarse glacial sediment, as was
expected, and finer sediment of semiglacial type, but there
were also layers of fine sediment typical of temperate climates.
It was the sort of sediment that is carried down by rivers from
ice-free continents. Here was a first surprise, then. Temper-
ate conditions had evidently prevailed in Antarctica in the
not distant past. The sediment indicated that not less than
four times during the Pleistocene Epoch, or during the last
million years, had Antarctica enjoyed temperate climates. (See
Figure XI, p. 306.)
Then, when this material was dated by Dr. Urry, it became
plain that the numerous climatic changes had occurred at
very short intervals. Moreover, it appeared that the last ice
age in Antarctica started only a few thousand years ago.
Hough wrote:
The log of core N-5 shows glacial marine sediment from the pres-
ent to 6,000 years ago. From 6,000 to 15,000 years ago the sediment is
fine-grained with the exception of one granule at about 12,000 years
ago. This suggests an absence of ice from the area during that period,
except perhaps for a stray iceberg 12,000 years ago. Glacial marine
sediment occurs from 15,000 to 29,500 years ago; then there is a zone
of fine-grained sediment from 30,000 to 40,000 years ago, again sug-
gesting an absence of ice from the sea. From 40,000 to 133,500 years
ago there is glacial marine material, divided into two zones of coarse-
and two zones of medium-grained texture.
THE ICE AGES 51
The period 133,000-173,000 years ago is represented by fine-grained
sediment, approximately half of which is finely laminated. Isolated
pebbles occur at 140,000, 147,000 and 156,000 years. This zone is in-
terpreted as recording a time during which the sea at this station was
ice free, except for a few stray bergs, when the three pebbles were
deposited. The laminated sediment may represent seasonal outwash
from glacial ice on the Antarctic continent.
Glacial marine sediment is present from 173,000 to 350,000 years
ago, with some variation in the texture. Laminated fine-grained sedi-
ment from 350,000 to 420,000 years ago may again represent rhythmic
deposition of outwash from Antarctica in an ice free sea. The bottom
part of the core contains glacial marine sediment dated from 420,000
to 460,000 years by extra-polation of the time scale from the younger
part of the core (225:257-59).
It should be realized that the Ross Sea, from which these
cores were taken, is a great triangular wedge driven right into
the heart of the continent of Antarctica, to within about
eight hundred miles of the pole. It follows that, when the
shores of the Ross Sea were free of ice, and if free-flowing
rivers were bringing down sediment from the interior, Ant-
arctica must have been very largely an ice-free continent.
Some of the fine sediment, it is true, does not indicate ice-free
conditions for the whole continent, but only for the sea itself.
The laminated sediment, consisting of distinct thin layers
each representing the deposition of one year, suggests the
results of a summer melting of an ice sheet not far from the
sea, with swollen streams of melt water carrying the sedi-
ment to the sea. Such conditions do not suggest any wide
deglaciation of Antarctica, though they do suggest conditions
very different from those prevailing now. On the other hand,
unlaminated deposits of fine sediment are consistent with a
general and even with a total deglaciation of Antarctica. So
far as we can see, such sediment can only have been brought
down to the sea by rivers flowing from the interior of the
continent. The very existence of such unfrozen rivers re-
quires the deglaciation of a part of the continent. One is free
to assume that the deglaciation applied to only a small area,
52 EARTH'S SHIFTING CRUST
but there is really no good reason to adopt this assumption
unless a cause can be shown for a local deglaciation.1
The importance of all this evidence is obvious when we
realize that, as late as 1 950, there appeared to be no question
but that the icecap in Antarctica was millions of years old.
According to Brooks, the geologists Wright and Priestly had
presented conclusive evidence of the beginning of the present
icecap as far back as the beginning of the Tertiary Period
(52:239), some 60 or 80 million years ago. Now we have evi-
dence of several periods of semiglacial or nonglacial condi-
tions in Antarctica in the Pleistocene Epoch alone. This is
sufficient to show us how little reliance can be placed upon the
estimated durations of hundreds of thousands or millions of
years for the glacial periods of the remote past.
We must realize, however, that the date found by Urry for
the beginning of the deposition of glacial sediment on the
1 An astonishing bit of evidence suggesting the idea of a temperate age in Ant-
arctica has been produced by Arlington H. Mallery, cartographer and archae-
ologist. Mr. Mallery solved the projection of an ancient map compiled in the
sixteenth century by the Turkish geographer Piri Reis, from maps one of which
is said to have been in the possession of Columbus, and the others of which
were said by Piri Reis to have been preserved in the East since the time of
Alexander the Great (who may have discovered them in Egypt). The projection
had long baffled scientists, including the explorer-scientist Nordenskjold, who
had spent seventeen years trying to solve it. When Mr. Mallery solved the pro-
jection he found that the map showed all the coasts of South America, a great
part of the coast of Antarctica, including Queen Maud Land and the Palmer
Peninsula, and Greenland and Alaska. It appeared that the mapping of Antarc-
tica had actually been done when the land was ice- free— before the icecap ap-
peared. There was no indication as to what ancient people could have made
the map, but Mr. Mallery concluded that the information on the map was at
least five thousand years old, and perhaps much o^der. The topographic fea-
tures on the map of Queen Maud Land corresponded remarkably to the fea-
tures deduced from seismic profiles made during one of the recent Antarctic
expeditions of the Navy. Mr. Mallery's statements were confirmed and sup-
ported by Mr. M. I. Walters, who, as a member of the Hydrographic Office, had
checked the map in detail, and by Father Daniel Linehan, Director of the
Weston Observatory of Boston College, who checked the seismic profile made
by the Navy against the data on the map. Mr. Mallery's findings were presented
in a radio broadcast by the Georgetown University Forum, Washington, D.C.,
in August, 1956. A verbatim report of the broadcast, with reproductions of the
map, may be obtained from the Forum.
THEICEAGES 53
bottom of the Ross Sea 6,000 years ago is not the date of the
beginning of the last change of climate in Antarctica. A con-
siderable time must have elapsed between the fall of tempera-
ture on the continent and the beginning of the deposition of
the glacial sediment. An icecap must grow to a considerable
thickness before it can start to move by gravity, and can start
to throw off icebergs at the coast. Moreover, we must suppose
that the change of climate must have been gradual at first. It
seems reasonable, therefore, to allow a period of the order
of about 10,000 years from the time the climate started to
change to the time when the glacial sediment began to be
deposited on the sea bottom. This is all the more likely since
most of the coasts of Antarctica seem to be bounded by moun-
tain chains, which the icecap would have to cross.
Where do these considerations lead us? They lead us to the
conclusion that the melting of the great icecap in North
America about 10,000 years ago and the beginning of the
massive advance of the Antarctic icecap may have been
roughly contemporary; that as one icecap melted, the other
one grew.
Let us pause to consider the implications of this astonish-
ing conclusion. For one thing, it is clear that no such change
as the growth or removal of even a considerable part of a
continental icecap covering 6,000,000 square miles of the
earth's surface can result from purely local causes. At present
the Antarctic icecap profoundly affects the climate of the
whole world. The great anticyclonic winds, blowing outward
from the continent in all directions, influence the directions
of ocean currents, and the climates of all the lands in the
Southern Hemisphere. The North American icecap was
equally a factor in k world climate. If one icecap appeared
when the other disappeared, then both of these great con-
temporary changes of climate must be supposed to have re-
sulted from some cause operating on the globe as a whole.
But what kind of cause could glaciate one continent and
deglaciate the other? It seems quite clear that only a shift of
the crust of the earth such as would have moved America
54 EARTH'S SHIFTING CRUST
away from one polar zone and Antarctica toward the other
one can adequately account for the facts. Moreover, it is true,
as can be seen from any globe, that a movement of the crust
sufficient to bring Hudson Bay down to its present latitude
from the pole would at the same time account for the glacia-
tion of all that half of Antarctica facing the Ross Sea.
There are a number of important conclusions to be drawn
from these Antarctic data, in addition to the remarkable con-
firmation of a displacement of the crust. One is that the rapid
rate of change indicated for the Wisconsin icecap may be
typical for the whole Pleistdcene, and therefore, very likely,
typical of older periods in the earth's history. Hardly less
important than this is the implication to be drawn from the
apparent fact that the ice ages, in these two instances, were
not contemporaneous. It follows, of course, that if the ice
ages we know most about were not contemporary in the two
hemispheres, there is no justification for assuming that those
we know little or nothing about were contemporary. Clearly,
with glacial periods so short, and the tempo of change so
rapid, there is no justification for claiming glaciation in the
two hemispheres hundreds of millions of years ago to have
been simultaneous. This theory, which constitutes a harmful
dogma of contemporary science, should now be abandoned,
and with it must go most of the current speculations about
the causes of ice ages.
I cannot conclude this chapter without warning the reader
that, however clear these facts may be, there are still some
who will insist that the Hough-Urry cores show that the re-
cent glaciations were simultaneous in the two hemispheres.
This argument is based on the strange period of high tempera-
ture that followed the ice age in North America, but was
world-wide in its effects. This warm period has been well es-
tablished, but its cause has been unknown. The essential facts
are given by Professor Flint:
. . . the evidence of the fossil plants, and, in addition, several en-
tirely independent lines of evidence, establish beyond doubt that the
climate (with some fluctuation) reached a maximum of warmth be-
THE ICE AGES 55
tween 6,000 and 4,000 years ago; since then (again with minor fluctua-
tions) it has become cooler and more moist down to the present time.
Apparently as recently as 500 B.C. the climate was still slightly warmer
than it is today. The warm, relatively dry interval of 2000 years' dura-
tion has been called the Climatic Optimum. It is the outstanding
fact of the so-called post-glacial climatic history (156:487).
Dr. Hough attempts to identify the last warm period in
Antarctica with this Climatic Optimum, but we have seen
that, according to his own core, the last temperate period in
Antarctica apparently began 15,000 years ago, and ended
6,000 years ago, thus enduring for some 9,000 years, while
the Climatic Optimum began 6,000 years ago, when the tem-
perate age was drawing to a close in Antarctica, and endured
for only 2,000 years. It seems to me, therefore, that there is
no good reason to identify the two.
For some time attempts were made to attack the reliability
of the ionium method. I raised the question of these attacks
in a conversation with Einstein and received assurance that
in his opinion the method was reliable. Ericson and Wollin
have recently shown that the results obtained by the ionium
method agree very well with results achieved by other relia-
ble means (Chapter IX). We shall have occasion to cite the
work of Soviet scientists who appear to have used the ionium
method successfully in the Arctic Ocean, and to have ob-
tained results in good agreement with other methods of dat-
ing. We shall see that they have found a warm period for the
Arctic to correspond with the warm period indicated for Ant-
arctica, and at about the same time, just as we should expect
if both areas lay outside of the polar circles when the last
North American icecap was centered at Hudson Bay.
Volchok and Kulp have recently published the results of
a study by which some sources of errors in the use of the ion-
ium method for dating have been identified. Their results
suggest that in some cases errors in dating may result from
the use of cores that have not been continuously deposited,
or that have been disturbed since their original deposition.
However, in the cases^of the Ross Sea cores cited above we
56 EARTH'S SHIFTING CRUST
have three cores taken some distance apart that seem, never-
theless, to agree pretty well with each other, even though
there are evidences of some disturbance, and their evidence
is strengthened by their agreement with the Arctic cores to
be discussed later on.
From our point of view, the precise accuracy of the dating
is less important than the evidence that, in very recent time,
there was deposition of temperate type sediment in the Ross
Sea off the Antarctic coast.
6. Conclusion
It is clear that none of the great glaciations of the past can
be explained by the theories hitherto advanced. The only
ice age that is adequately explained is the present ice age in
Antarctica. This is excellently explained. It exists, quite obvi-
ously, because Antarctica is at the pole, and for no other
reason. No variation of the sun's heat, no galactic dust, no
volcanism, no subcrustal currents, and no arrangements of
land elevations or sea currents account for the fact. We may
conclude that the best theory to account for an ice age is
that the area concerned was at a pole. We thus account for
the Indian and African ice sheets, though the areas once occu-
pied by them are now in the tropics. We account for all ice
sheets of continental size in the same way.
Stokes has provided an excellent list of specifications for a
satisfactory ice age theory, every one of which is met by the
assumption of crust displacements as the fundamental cause
(405:815-16):
a. An initiating event or condition.
b. A mechanism for cyclic repetitions or oscillations within
the general period of glaciation.
c. A terminating condition or event.
d. It should not rely upon unprovable, unobservable, or
unpredictable conditions, when well-known or more
simple ones will suffice.
THE ICE AGES 57
e. It must solve the problem of increased precipitation
with colder climate.
f. The facts call for a mechanism that either increases the
precipitation or lowers the temperature very gradually
over a period of thousands of years.
It is evident that a displacement of the crust could initiate
an ice age by moving a certain region into a polar zone, while
a later displacement could end the ice age by moving the
same area away from the polar zone. The increased precipita-
tion and the oscillations of the borders of the ice sheets can
be explained by the atmospheric effects that would result
from volcanism associated with the movement of the crust.
These effects will be discussed in later chapters.
Ill : ANCIENT CLIMATES
In the last chapter it was argued that the ice ages can be
explained only by the assumption of frequent displacements
of the earth's crust. The ice ages, however, represent only one
side of the problem. If they are instances of extremely cold
climates distributed in an unexplained manner on the earth's
surface, there were also warm climates whose distribution is
equally unexplained.
In connection with these warm climates in the present
polar regions, there arises a contradiction of an especially
glaring character. On the one hand there is evidence that the
distribution of plants and animals in the past did not, as a
rule, follow the present arrangements of the climatic zones.
On the other hand, the trend of the new evidence is to show
that climatic zones have always been about as clearly dis-
tinguished by temperature differences as they are today. This
is in flat contradiction to the assumption, still widely held,
that the earth, during most of geological history, did not
possess clearly demarcated climatic zones. We are forced to
conclude that, since many ancient plants and animals were
not distributed according to the present climatic zones, the
zones themselves have changed position on the earth's surface.
This requires, as we have seen, that the surface shall have
changed position relative to the axis of rotation. We shall
now examine the evidence that supports this conclusion.
/. Ages of Bloom in Antarctica
1 have suggested that in very recent time, no more than
10,000 years ago, a large part of Antarctica may have been
ice-free. If this interpretation of the marine cores from the
Ross Sea is questioned by the conservative-minded, there
ANCIENT CLIMATES 59
can, however, be no dispute whatever about the more distant
past climates of Antarctica. Those who may be inclined to
disbelieve that Antarctica could have possessed a temperate
climate 10,000 years ago must be reminded of the evidence
that Antarctica has many times possessed such a climate.
So far as we know at present, the very first evidence of an
ice age in Antarctica comes from the Eocene Epoch (52:244).
This was barely 60,000,000 years ago. Before that, for some
billion and a half years, there is no suggestion of polar condi-
tions, though very many earlier ice ages existed in other parts
of the earth. Henry, in The White Continent, cites evidence
of the passing of long temperate ages in Antarctica. He de-
scribes the Edsel Ford Mountains, discovered by Admiral
Byrd in 1929. These mountains are of nonvolcanic, folded
sedimentary rocks, the layers adding up to 15,000 feet in
thickness. Henry suggests that they indicate long periods of
temperate climate in Antarctica:
The greater part of the erosion probably took place when Antarctica
was essentially free of ice, since the structure of the rocks indicates
strongly that the original sediment from which they were formed was
carried by water. Such an accumulation calls for an immensely long
period of tepid peace in the life of the rampaging planet (206:113).
Most sedimentary rocks are laid down in the sea, formed
of sediment brought down by rivers from near-by lands. The
lands from which the Antarctic sediments were brought seem
to have disappeared without a trace, but of the sea that once
existed where there is now land we have plenty of evidence.
Brooks remarks:
... In the Cambrian we have evidence of a moderately warm sea
stretching nearly or right across Antarctica, in the form of thick lime-
stones very rich in reef-building Archaeocyathidae (52:245).
Millions of years later, when these marine formations had
appeared above the sea, warm climates brought forth a luxu-
riant vegetation in Antarctica. Thus, Sir Ernest Shackleton
is said to have found coal beds within 200 miles of the South
Pole (71:80), and later, during the Byrd expedition of 1935,
60 EARTH'S SHIFTING CRUST
geologists made a rich discovery of fossils on the sides of lofty
Mount Weaver, in Latitude 86° 58' S., about the same dis-
tance from the pole, and two miles above sea level. These
included leaf and stem impressions, and fossilized wood. In
1952 Dr. Lyman H. Dougherty, of the Carnegie Institution
of Washington, completing a study of these fossils, identified
two species of a tree fern called Glossopteris, once common
to the other southern continents (Africa, South America,
Australia), and a giant tree fern of another species. In addi-
tion, he identified a fossil footprint as that of a mammallike
reptile. Henry suggests that this may mean that Antarctica,
during its period of intensive vegetation, was one of the most
advanced lands of the world as to its life forms (207).
Soviet scientists have reported finding evidences of a trop-
ical flora in Graham Land, another part of Antarctica, dating
from the early Tertiary Period (perhaps from the Paleocene
or Eocene) (364:13).
It is, then, little wonder that Priestly, in his account of his
expedition to Antarctica, should have concluded:
. . . There can be no doubt from what this expedition and
other expeditions have found that several times at least during past
ages the Antarctic has possessed a climate much more genial than that
of England at the present day , . . (34913:210).
Further evidence is provided by the discovery by British
geologists of great fossil forests in Antarctica, of the same type
that grew on the Pacific coast of the United States 20,000,000
years ago (206:9). This, of course, shows that after the earliest
known Antarctic glaciation in the Eocene, the continent did
not remain glacial, but had later episodes of warm climate.
Dr. Umbgrove adds the observation that in the Jurassic
Period the flora of Antarctica, England, North America, and
India had many plants in common (430:263).
There is one group of theories to which we cannot appeal
because of their inherent and obvious weaknesses. These
are the theories that try to explain warm and cold periods in
Antarctica by changes in land elevations, changes in the
ANCIENT CLIMATES 6l
directions of ocean currents, changes in the intensity of solar
radiation, and the like. It is obvious, for instance, that no
hypothetical warm currents could make possible the existence
of warm climates in the center of the great Antarctic conti-
nent if that continent were at the pole, and if by some miracle
Antarctica did become warm, how possibly could forests have
flourished there deprived of sunlight for half the year?
2. Warm Ages in the North
The Arctic regions have been more accessible, and conse-
quently they have been more thoroughly explored, than the
Antarctic. It was from them that the first evidence came
pointing unmistakably to shifts in the geographical positions
of the poles. Most of the theories developed by those defend-
ing the dogma of the permanence of the poles were specially
designed to explain these facts, or rather, as it now seems, to
explain them away.
One method of explaining away the evidence was to sug-
gest that the plants and animals of past geological eras, even
though they belonged to similar genera or families as living
plants, and closely resembled them in structure, may have
been adapted to very different climates. This argument often
had effect, for no one could exclude the possibility that, in a
long geological period, species might make successful adjust-
ments to different climatic conditions. Where single plants
were involved such a possibility could not be dismissed.
Where, however, whole groups of species, whole floras and
faunas, were involved, there was increased improbability that
they could all have been adjusted at any one time to a radi-
cally different environment from that in which their de-
scendants live today. For this reason, and because the
structure of plants has a definite relationship to conditions
of sunlight, heat, and moisture, biologists have abandoned
this method of explaining the facts. Dr. Barghoorn, for ex-
62 EARTH'S SHIFTING CRUST
ample, says that fossil plants are reliable indicators of past
climate (375:237~38)-
It may be worth while to review, very briefly, some high
points of the climatic history of the Arctic and sub-Arctic
regions, beginning with one of the oldest periods, the Devo-
nian, and coming down by degrees to periods nearer our
own. (During this discussion the reader may find it helpful
to refer to the table of geological periods, page 23.)
The Devonian evidence is particularly rich, and includes
both fauna and flora. Dr. Colbert, of the American Museum
of Natural History, has pointed out that the first known
amphibians have been found in this period in eastern Green-
land, near the Arctic Circle, though they must have required
a warm climate (375:256). Many species of reef corals, which
at present require an all-year sea-water temperature of not
less than 68° F. (102:108), have been found in Ellesmere Is-
land, far to the north of the Arctic Circle (399:2). Devonian
tree ferns have been found from southern Russia to Bear
Island, in the Arctic Ocean (177:360). According to Barg-
hoorn, assemblages of Devonian plants have been found in
the Falkland Islands, where a cold climate now prevails, in
Spitzbergen, and in Ellesmere Island, as well as in Asia and
America (375:240). In view of this, he remarks:
The known distribution of Devonian plants, especially their diversi-
fication in high latitudes, suggests that glacial conditions did not exist
at the poles (375:240).
In the following period, the Carboniferous, we have evi-
dence summed up by Alfred Russel Wallace, co-author, with
Darwin, of the theory of evolution:
In the Carboniferous formation we again meet with plant remains
and beds of true coal in the Arctic regions. Lepidodendrons and
calamites, together with large spreading ferns, are found at Spitz-
bergen, and at Bear Island in the extreme north of Eastern Siberia;
while marine deposits of the same age contain an abundance of large
stony corals (446:202).
In the Permian, following the Carboniferous, Colbert re-
ports a find of fossil reptiles in what is now a bitterly cold
ANCIENT CLIMATES 6j
region: ' 'Large Permian reptiles . . . are found along the
Dvina River of Russia, just below the Arctic Circle, at a
North Latitude of 65° " (375:259). Dr. Colbert explains that
these reptiles must have required a warm climate. In sum-
ming up the problem of plant life for the many long ages
of the Paleozoic Era, from the Devonian through the Per-
mian, Barghoorn says that it is "one of the great enigmas" o£
science (375:*43>-
Coming now to the Mesozoic Era (comprising the Triassic,
Jurassic, and Cretaceous Periods), Colbert reports that in the
Triassic some amphibians (the Labyrinthodonts) ranged all
the way from 40° S. Lat. to 80° N. Lat. About this time the
warm-water Ichthyosaurus lived at Spitzbergen (375:262-64).
For the Jurassic, Wallace reports:
In the Jurassic Period, for example, we have proofs of a mild arctic
climate, in the abundant plant remains of East Siberia and Amurland.
. . . But even more remarkable are the marine remains found in
many places in high northern latitudes, among which we may espe-
cially mention the numerous ammonites and the vertebrae of huge
reptiles of the genera Ichthyosaurus and Teleosaurus found in Jurassic
deposits of the Parry Islands in 77° N. Lat. (446:202).
For the Cretaceous Period, A. C. Seward reported in 1932
that "the commonest Cretaceous ferns [of Greenland] are
closely allied to species ... in the southern tropics" (373:
363-71). Gutenberg remarks: "Thus, certain regions, such
as Iceland or Antarctica, which are very cold now, for the late
Paleozoic or the Mesozoic era show clear indications of what
we would call subtropical climate today, but no trace of
glaciation; at the same time other regions were at least tempo-
rarily glaciated'1 (194:195). This evidence, linked in this way
with the problem of the ice ages we have already discussed,
reveals the existence of a single problem. Ice ages in low
latitudes, and warm ages near the poles, are, so to speak, the
sides of a single coin. A successful theory must explain both
of them.
Following the Cretaceous, the Tertiary Period shows the
same failure of the fauna and flora to observe our present
64 EARTH'S SHIFTING CRUST
climatic zones. Scott, for example, says: "The very rich floras
from the Green River shales, from the Wilcox of the Gulf
Coast and from the Eocene of Greenland, show that the
climate was warmer than in the Paleocene, and much warmer
than today" (372:103).
In this Eocene Epoch we find evidence of warm climate in
the north that is truly overwhelming. Captain Nares, one of
the earlier explorers of the Arctic, described a twenty-five-foot
seam of coal that he thought was comparable in quality to
the best Welsh coal, containing fossils similar to the Miocene
fossils of Spitsbergen. He saw it near Watercourse Bay, in
northern Greenland (319:!!, 141-42). Closer examination
revealed that it was, in reality, lignite. Nevertheless, the con-
tained fossils clearly indicated a climate completely different
from the present climate of northern Greenland:
The Grinnell Land lignite indicates a thick peat moss, with prob-
ably a small lake, with water lilies on the surface of the water, and
reeds on the edges, and birches and poplars, and taxodias, on the
banks, with pines, firs, spruce, elms and hazel bushes on the neighbor-
ing hills . . . (319:11,335).
Brooks thinks that the formation of peat bogs requires a
rainfall of at least forty inches a year, and a mean tempera-
ture above 32° F. (52:173). This suggests a very sharp con-
trast with present Arctic conditions in Grinnell Land.
DeRance and Feilden, who did the paleontological work
for Captain Nares, also mention a Miocene tree, the swamp
cypress, that flourished from Central Italy to 82° N. Lat., that
is, to within five hundred miles of the pole (319:!!, 335).
They show that the Miocene floras of Grinnell Land, Green-
land, and Spitzbergen all required temperate climatic condi-
tions, with plentiful moisture. They mention especially the
water lilies of Spitzbergen, which would have required flow-
ing water for the greater part of the year (319:!!, 336).
In connection with the flora of Spitzbergen, and the fauna
mentioned earlier, it should be realized that the island is in
polar darkness for half the year. It lies on the Arctic Circle,
as far north of Labrador as Labrador is north of Bermuda.
Wallace describes the flora of the Miocene. He points out
that in Asia and in North America this flora was composed
of species that apparently required a climate similar to that
of our southern states, yet it is also found in Greenland at
70° N. Lat., where it contained many of the same trees that
were then growing in Europe. He adds:
But even farther North, in Spitsbergen, 78° and 79° N. Lat. and
one of the most barren and inhospitable regions on the globe, an
almost equally rich fossil flora has been discovered, including several
of the Greenland species, and others peculiar, but mostly of the same
genera. There seem to be no evergreens here except coniferae, one of
which is identical with the swamp-cypress (Taxodium distichum) now
found living in the Southern United States. There are also eleven
pines, two Libocedrus, two Sequoias, with oaks, poplars, birches,
planes, limes, a hazel, an ash, and a walnut; also water lilies, pond
weeds, and an Iris— altogether about a hundred species of flowering
plants. Even in Grinnell Land, within 8i/£ degrees of the pole, a
similar flora existed . . . (446:182-84).
It has been necessary to dwell at length on the evidence of
the warm polar climates, because this is important for the
discussion that follows. Too often, in theoretical discussions,
the specific nature of the evidence tends to be lost sight of.
3. Universal Temperate Climates—A Fallacy
The evidence I have presented above (and a great deal more,
omitted for reasons of space) has long created a dilemma for
geology. Only two practical solutions have offered themselves.
One is to shift the crust, and the other is to suggest that
climatic zones like the present have not always existed. It is
often suggested that the climates have been very mild virtu-
ally from pole to pole, at certain times. The extent to which
this theory is still supported is eloquent evidence of the
power of the "dogma" of the permanence of the poles. When
one inquires as to the evidence for the existence of such
warm, moist climates, a peculiar situation is revealed. There
is no evidence except the fossil evidence that the theory is
66 EARTH'S SHIFTING CRUST
supposed to explain. Could there be a better example of
reasoning in a circle? Colbert cites evidence that the Devo-
nian animals were spread all over the world, and then re-
marks that therefore ". . . it is reasonable to assume . . .
that the Devonian Period was a time of widely spread equable
climates, a period of uniformity over much of the earth's
surface" (375:255). According to him, the same situation held
true through the Paleozoic and Mesozoic, and even much
later periods (375:268). Other paleontologists reasoned in the
same way. Goldring, for example, remarked: "The Carbonif-
erous plants had a world-wide distribution, suggesting rather
uniform climatic conditions" (177:362). She drew the same
conclusions from the world-wide distribution of Jurassic flora
(177:363). But it is clear that when a theory has been con-
cocted to explain a given set of facts, those facts themselves
cannot be adduced as proof of the theory. This is circular
reasoning. A theory must, first, be shown to be inherently
reasonable, and then it must be supported by independent
facts.
Is such a theory inherently reasonable? The answer is that
it is not. It involves, in the first place, ignoring the astro-
nomical relations of the earth. The theory requires us to
assume the existence of some factor powerful enough to coun-
teract the variation of the sun's heat with latitude. As Pro-
fessor Bain, of Amherst, has pointed out, in an article to be
discussed further below,
. /•'. The thermal energy arriving at the earth's surface per day
per square centimeter averages 430 gram calories at the equator but
declines to 292 gram calories at the 4Oth parallel and to 87 gram
calories at the Both parallel . . . (18:16).
What force sufficiently powerful to counteract that fact of
astronomy can be suggested, and, more important, supported
by convincing evidence?
It was thought at first that universal temperate climates
might be accounted for by the theory of the cooling of the
earth. Those who proposed this theory (253, 292) argued that
ANCIENT CLIMATES 67
in earlier ages the earth was hotter, the ocean water evapo-
rated much more rapidly, and it formed thick clouds that
reflected the sun's radiant energy back into space. The cloud
blanket shut out the sun's radiation but kept in the heat that
radiated from the earth itself, and this acted to distribute the
heat evenly over the globe. The cloud blanket must have
been thick enough to make the earth a dark, dank, and dismal
place. Since, as Dr. Colbert shows, fossils are found outside
the present zones appropriate to them even in recent geolog-
ical periods, such conditions must have obtained during
about 90 per cent of the earth's whole history, and most of
the evolution of living forms must have taken place in them.
For a number of reasons, including the difficulty of ex-
plaining how plants can have evolved without sunlight, this
theory has been abandoned. We have also seen that the idea
that the earth was even hotter than now has recently been
undermined. This has destroyed the solidity of the theory's
basic assumption.
The fact that the theory never was reasonable is shown
from Coleman's arguments against it, advanced more than a
quarter of a century ago. He pointed out that not only are
ice ages known from the earliest periods (from the Pre-
Cambrian) but there is evidence that some of these very
ancient ice ages were even more intensely cold than the
recent ice age that came to an end 10,000 years ago (87:78).
No less than six ice ages are known from the Pre-Cambrian
(430:260). The evidence of one of these Pre-Cambrian or
Lower Cambrian ice ages is interestingly described by
Brews ter:
In China, in the latitude of northern Florida, there is a hundred
and seventy feet of obvious glacial till, scratched boulders and all,
and over it lie sea-floor muds containing lower Cambrian trilobites,
the whole now altered to hard rock (45:204).
It is obvious that such ice ages (and evidences of more of
them are frequently coming to light) are in conflict with the
theory of universal equable climates. Some of them are found
68 EARTH'S SHIFTING CRUST
right in the midst of periods thought to have been especially
warm, such as the Carboniferous.
Coleman presents other geological evidence against the
theory. The fact that most of the fossils found are those of
warm-climate creatures is, he thinks, misleading. Plants and
animals are more easily fossilized in warm, moist climates
than they are in cold, arid ones. Fossilization, even under the
most favorable conditions, is a rare accident. The fauna and
flora of the temperate and arctic zones of the past were sel-
dom preserved (87:252). Thus, while the finding of fossils of
warm-climate organisms all over the earth is an argument
against the permanence of the present arrangement of the
climatic zones, it is not an argument for universal mild
climates.
Another argument against such climates may be based
upon the evidences of desert conditions in all geological
periods. These imply world-wide variations in climate and
humidity. Both Brooks (52:24-25, 172) and Umbgrove (430:
265) stress the importance of this evidence. One of the most
famous formations of Britain—the Old Red Sandstone— is,
apparently, nothing but a fossil desert. Coleman points to
innumerable varved deposits in many geological periods as
evidence of seasonal changes (87:253), which, of course, imply
the existence of climatic zones.
Ample evidence of the existence of strongly demarcated
climatic zones through the earth's whole history (at least since
the beginning of the deposition of the sedimentary rocks)
comes from other sources. Barghoorn cites the evidence of
fragments of fossil woods from late Paleozoic deposits in the
Southern Hemisphere that show pronounced ring growth,
indicating seasons; he also points out that in the Permo-Car-
boniferous Period floras existed that were adapted to very
cold climate (375:242). Colbert himself reports good evidence
of seasons in the Cretaceous Period, in the form of fossils of
deciduous trees (375:265).
Umbgrove cites the geologist Berry, who states that the
fossilized woods from six geological periods, from the Devo-
ANCIENT CLIMATES 69
nian to the Eocene, show well-marked annual rings, indicat-
ing seasons like those of the present time^ Furthermore, Berry
goes on to say:
Detailed comparisons of these Arctic floras with contemporary floras
from lower latitudes . . . show unmistakable evidence for the exist-
ence of climatic zones . . . (430:266).
Brooks concludes, on the basis of Berry's evidence, that cli-
matic zones existed in the Eocene (52:24). Ralph W. Chancy,
after a study of the fossil floras of the Tertiary Period (from
the Eocene to the Pliocene), concluded that climatic zones
existed (72:475) during that whole period. The distinguished
meteorologist W. J. Humphreys, whose fundamental work,
The Physics of the Air, remains a classic, remarked in 1920
that there was no good evidence of the absence of climatic
zones from the beginning of the geological record. Finally,
Dr. C. C. Nikiforoff, an expert on soils (both contemporary
and fossil soils), has stated that "In all geological times there
were cold and warm, humid and dry climates, and their ex-
tremes presumably did not change much throughout geo-
logical history" (375:191). We will return, below, to the
significance of fossil soils, and present other evidence showing
persistence of sharply demarcated climatic zones during the
earth's history. But where, at this point, does the evidence
leave us?
On the one hand, the evidence shows that the plants and
animals of the past were distributed without regard to the
present direction of the climatic zones. I have been unable to
do more than suggest the immensity of the body of evidence
supporting this conclusion. On the other hand, the attempt
to deny the existence, in the past, of sharply demarcated cli-
matic zones like those of the present has failed. It may even
be said to have failed sensationally. There is no scrap of evi-
dence for it, except the evidence it is supposed to explain,
while, on the other hand, it is in contradiction both with
the fundamentals of astronomy and the preponderance of
geological evidence.
70 EARTH'S SHIFTING CRUST
So we are left with a clear-cut conclusion: Climatic zones
have always existed as they exist today, but they have fol-
lowed different paths on the face of the earth. If changes in
the position of the axis of rotation of the earth, and of the
earth upon its axis, are equally impossible, and if the drift
of continents individually is rendered extremely improbable
for numerous weighty reasons, then we are forced to the con-
clusion that the surface of the earth must often have been
shifted over the underlying layers.
4. The Eddington-Pauly Suggestion
Another suggestion for displacements of the earth's crust, to
which I have briefly referred, should now be further dis-
cussed. Its author, Karl A. Pauly, has contributed new lines
of evidence in support of such shifts. He has based his dis-
placement theory on Eddington's suggestion that the earth's
crust may have been displaced steadily through time by the
effects of tidal friction. Eddington's idea has serious weak-
nesses, but the evidence for displacements presented by Pauly
is most impressive.
" Pauly suggests that a study of the elevations above sea level
of the terminal moraines of mountain glaciers in all latitudes
can establish a correlation of elevation with latitude. It is
true that many factors influence the distance a mountain
glacier may extend downward toward sea level, but latitude
is one of them, and by using a sufficient number of cases it is
possible to average out the other factors, and arrive at the
average elevation of mountain glacier moraines above sea
level for each few degrees of latitude from the equator toward
the poles. This gives us a curve that makes it possible to com-
pare the elevations of the terminal moraines of mountain
glaciers that existed during the Pleistocene Period. Pauly
finds that these moraines do not agree with the curve, indi-
cating unmistakably a displacement of the earth's crust (342:
89).
ANCIENT CLIMATES 71
Pauly cites another impressive line of evidence in support
of his conclusions. He has compared the locations of coal de-
posits of several geological periods (many of which are now
in polar regions) with the locations of icecaps for the same
periods. He lists 34 coal deposits regarded as of Jurassic-
Liassic age and 17 of Triassic-Thaetic age, and finds that, if
it is assumed that the centers of the icecaps of that time were
located at the poles, then these coal deposits would have been
located within or just outside the tropics, as would be correct
He says:
The very definite location of these coal deposits within the Tria-
Jura tropical and subtropical zones cannot be mere coincidence. The
distribution indicates the lithosphere has shifted (342:96).
Of the Permo-Carboniferous coal deposits, which, he
points out, are very widely distributed over the earth, he
says that "95 out of 105 listed in The Coal Resources of the
World lie within or just outside of the tropics as determined
by the assumption that the North or South Pole lay under the
center of one of the Permo-Carboniferous ice sheets" (342:
97)-
5. The Contribution of George W. Bain
Not long ago Professor George W. Bain, of Amherst, in an
article in the Yale Scientific Magazine (18), went considerably
beyond the categories of evidence that we have so far con-
sidered. He discussed the specific chemical processes con-
trolled by sunlight and varying according to latitude, and the
remanent chemicals typical of soils developed in the different
climatic zones. He extended this sort of analysis also to
marine sediments.
Bain's approach to the problem of evidence of climatic
change has many advantages. It avoids, for one thing, the ob-
jection that has been raised against some of the plant evi-
dence: that plants of the past may have been adjusted to
72 EARTH'S SHIFTING CRUST
climates different from those in which their modern descend-
ants live. I believe his method establishes beyond question
the existence of climatic zones all through the geologic past.
Dr. Bain begins with a precise definition of each climatic
zone in terms of the quantities of the sun's heat reaching the
earth's surface. He points out that, as is known, the seasonal
variation of this heat increases with distance from the equator
(18:16). He then describes the global wind pattern resulting
from this distribution of the sun's energy, defining clearly
the conditions of the horse latitudes, in which most of the
earth's deserts are found, and the meteorology of the polar
fronts. He shows that there are distinct and different com-
plete chemical cycles in each of these areas, and correspond-
ing cycles in the sea. Many of the chemical compounds pro-
duced in each of these areas are included, naturally, in the
rocks formed from the sediments, and they remain as perma-
nent climatic records.
It is impossible, because of limitations of space, to do jus-
tice to Dr. Bain's comprehensive approach to this question.
There appears to be no room for doubt, however, that great
differences exist between the mineral components of the
different climatic zones, as determined by the amount of the
sun's radiant heat. With regard to the polar soils, in addition,
it is noteworthy that they are developed in circles on the
earth's surface, rather than in bands. Temperate and tropical
soils are, of course, found in bands, since the zones are bands
that encircle the earth.
It will be clear to the reader that Dr. Bain has established
a sound method for the study of the climates of the past. He
has applied his method to the study of the climates of two
periods, the Jurassic-Cretaceous and the Carboniferous-Per-
mian, with very significant results. He has concluded, first,
that climatic zones, representing the different distributions of
solar heat, existed in those periods just as at present. This is
proved by the specific remanent chemicals included in these
rocks, which differ exactly as do the sediments of the different
ANCIENT CLIMATES 73
zones at the present time. This is, of course, fatal for the
theory of universal equable climates.
His second conclusion, of even greater importance, is that
the directions of the climatic zones have changed enormously
in the course of time. He finds the equator running through
the New Siberian Islands (in the Arctic Ocean) in the Permo-
Carboniferous Period, and North and South America lying
tandem along it (18:17). The evidence he uses seems to
establish his essential point (and ours) that the climatic zones
themselves have shifted their positions on the face of the
earth.
Dr. Bain has drawn some interesting further conclusions.
He states that the earth's crust must have been displaced over
the interior layers, and that "fixity of the axis of the earth
relative to the elastic outer shell just is not valid. . . ." (18:
46). He points to the fossil evidence of the cold zones (dis-
tributed in circular areas) and says, ". . . The recurrent
change in position of these rings through geologic time can
be accounted for now only on the basis of change in the posi-
tion of the elastic shell of the earth relatively to its axis of
rotation" (18:46).
6. The Contribution of T. Y. H. Ma
Dr. Bain pointed out, in the paper above mentioned, that
among other indications of latitude, sea crustaceans and
corals may indicate latitude either by the presence or absence
of evidence of seasonal variations in growth. It happens that
corals have been very thoroughly investigated from precisely
this point of view.
By a remarkable parallelism of development, another the-
ory of displacement of the earth's crust took shape on the
opposite side of the earth at about the same time that Mr.
Campbell and I started on our project. Professor Ting Ying
H. Ma, an oceanographer, then at the University of Fukien,
China, came to the conclusion, after many years of study of
74 EARTH'S SHIFTING CRUST
fossil corals, that many total displacements of the earth's
whole outer mantle must have taken place. I did not become
aware of Professor Ma's work until I was introduced to it by
Dr. David Ericson, of the Lament Geological Observatory, in
1954. Dr. Ericson has, in fact, taken a leading role in intro-
ducing Professor Ma's work to American scientists.
For about twenty years previous to the time I mention,
Professor Ma had intensively pursued the study of living
and fossil reef corals. He very early noticed that characteristic
of reef corals referred to by Dr. Bain, but hitherto ignored
by writers on corals. He saw that, at distances from the
equator, there were seasonal differences in the rates of coral
growth, and that the evidences of these were preserved in the
coral skeleton. Specifically, he observed that in winter the
coral cells are smaller and denser; in summer they are larger
and more porous. Together, these two rings make up the
growth for one year.
Studying living coral reefs in various parts of the Pacific,
comparing, measuring, and tabulating coral specimens of
innumerable species, making photographic studies of the
coral skeletons, Professor Ma established that the rates of
total annual coral growth for identical or similar species
within the range of the coralline seas increased with prox-
imity to the equator, and that seasonal variation in growth
rates increased with distance from the equator.
Other writers on corals have pointed out that there are
numerous individual exceptions and irregularities in coral
growth rates, deriving from the fact that the coral polyps feed
upon floating food, which may vary in quantity from place
to place, from day to day, and even from hour to hour (125:
20-21; 298:52-53). Professor Ma, however, has guarded him-
self against error by a quantitative and statistical approach.
In several published volumes of coral studies (285-290) he
has compiled tables running into hundreds of pages, and his
studies have involved thousands of measurements.
When this indefatigable oceanographer had worked out
these relations of growth with latitude, he possessed an effeo
ANCIENT CLIMATES 75
tive tool with which to investigate the climates of the past. It
was possible now to arrive at a very good idea of the condi-
tions under which fossil corals grew. Professor Ma studied
hundreds of specimens of fossil corals from many of the geo-
logical periods. He devoted entire separate volumes to each
of the Ordovician, Silurian, Devonian, Cretaceous, and Ter-
tiary Periods (285-289).
As Ma assembled the coral data for past periods, it became
plain to him that the total width of the coralline seas had
never varied noticeably from the beginning of the geological
record. Not only was the existence of seasons, of climatic
zones, in the oldest geological periods clearly indicated; it
was also indicated that the average temperatures of the re-
spective zones were about the same as at present.
The second result of Ma's studies was to establish that the
positions of the ancient coralline seas and, therefore, of the
ancient equators were not the same as at present. They
changed from one geological period to another. Ma first came
to the conclusion that this could be explained only by the
theory of drifting continents. Down to about 1949 he sought
to fit the evidence into that theory. By 1949, however, the
continuing accumulation of the evidence led him to adopt
the theory of total displacements of all the outer shells of the
earth over the liquid core. By some instinct of conservatism,
however, he did not abandon the theory of floating conti-
nents, but combined it with the new theory.
Ma's coralline seas ran in all directions; one of his equators
actually bisected the Arctic Ocean. But he had great diffi-
culty in matching up his equators on different continents.
If, for example, he traced an equator across North America,
he could not match it with an equator for the same period
on the other side of the earth, to make a complete circle of
the earth. He therefore supposed that the continents them-
selves had been shifting independently, and this had had the
effect of throwing the ancient equators out of line. He there-
fore allowed, for each period, enough continental drift to
bring the equators into line, and it seemed, when he did
76 EARTH'S SHIFTING CRUST
this, that in successive geological periods he did have increas-
ing distances between the continents, as if the drift had been
continuous.
Subsequently, Professor Ma developed his theory into a
complete system, which is most interesting, and yet to which,
I think, serious objections may be raised.
Corals are, according to Ma, excellent indicators of the
climate for the time in which they grew, but, by the nature
of the case, since corals grow only in shallow water, and grow
upwards only as far as the surface, the period of time repre-
sented by a single fossil coral reef is of the order of a few
thousand years only, as compared with the millions of years
embraced by a geological period.
How short the continuous growth of a coral reef may be
is indicated by numerous studies of the coral reefs of the
Pacific. A. G. Mayor, for example, says:
. . . The modern reefs now constituting the atolls and barriers of
the Pacific could readily have grown upward to sea-level from the
floors of submerged platforms since the close of the last glacial epoch
At Pago Pago Harbor borings were made down to the
basalt underlying the reef, and after estimates of the growth
rate were arrived at, the age of the reef (Utelei) was esti-
mated at 5,000 years. When these spans are compared with
those of entire geological periods of the order of 20,000,000
or 30,000,000 years, it is clear how fragile must be any con-
clusions based on the assumption that a given coral reef in
Europe was contemporary with another one in North Amer-
ica. It is quite impossible in the present state of our knowl-
edge to decide that they were in fact contemporary.
This means that Ma's corals for a period like the Devonian
may be indications of different equators that existed at differ-
ent times during that period of 40,000,000 years. Therefore
it is obvious that thousands of coral specimens would be re-
quired to give any certainty as to the actual climatic history
of an entire geological period.
ANCIENT CLIMATES 77
Very possibly Ma could have avoided combining the two
different theories— the slipping of the shell of the earth and
the drifting of continents— if he had supposed a sufficiently
frequent slipping of the crust. The frequency of the displace-
ments suggested by the theory presented in this book, which
would involve many different equators in a single geological
period, would remove his difficulties. As it is, he has to face
all the geophysical and geological objections to the drifting
continent theory, as well as difficulties with his displacement
theory.
7. On the Rate of Climatic Change
Studies appear from time to time in which attempts are made
to trace climatic changes in specified areas over periods of
millions of years. In one of these, for example (72), the con-
clusion is reached that there was a gradual cooling of the
climate during a great many million years of the Tertiary
Period. It is true that no cause of such a progressive cooling
can be pointed to; neither is there any explanation as to why
the climatic change had to be so gradual. It is simply assumed
that the climatic change had to be gradual, and that the cause
of the change had to be such as to explain imperceptible
climatic changes over millions of years of time.
It is important to define as clearly as possible the nature
of the evidence on which these conclusions are based. In the
example I am considering, the following facts have decisive
importance:
a. The period of time involved in an alleged cooling of
the climate is of the order of 30,000,000 years.
b. Wherever reference is made to the specific strata of rock
selected for analysis of the climatic evidence (consisting
of included fossils), it is clear that the time required for
the deposition of a particular layer was of the order of
10,000 years.
78 EARTH'S SHIFTING CRUST
c. It follows that during 30,000,000 years it would be pos-
sible to have about 3,000 different layers of sedimentary
rock.
d. A vast majority of these layers cannot be sampled, either
because they no longer exist, or because they do not
contain fossils, or simply because of the amount of work
involved.
e. As a result, only the most unsatisfactory kind of spot
checking is possible. Perhaps a dozen strata out of 3,000
may be studied, and from these it must be obvious that
no dependable climatic record can be established.
f. Even with the unsatisfactory spot checking so far at-
tempted, reversals of climatic trends have been ob-
served (72).
g. Climatic conditions indicated by a layer of sediments
deposited during a brief period of time in one location
cannot be assumed to indicate the direction of climatic
change over a great region, or over the whole earth. It
seems quite as reasonable to suppose that climatic
change in other regions at the same time was in a differ-
ent direction. Furthermore, it cannot be assumed that
two sedimentary deposits in different areas are of the
same age because they both indicate climatic change in
the same direction.
It must be concluded that all claims for gradual climatic
changes in the same direction over long periods of time and
over great areas are unsupported by convincing evidence.
The existence of such long-term trends can be supported
by no reasonable hypothesis. We are left with the conclusion
that climatic change has probably taken place within rela-
tively short periods of time, and possibly in opposite direc-
tions for different areas at the same time, as, indeed, would
be a natural consequence of displacements of the earth's
crust.
IV : THE MOUNTAINS
PART I. The Folding and Fracturing of the Crust
By far the most magnificent features of the earth's crust are
the lofty mountain ranges that are found on all the conti-
nents, exciting the wonder of man, and those other, equally
tremendous mountain ranges that lie drowned in the silent
depths of the sea. These mountain ranges carry in their in-
tricate formations much of the history of the earth's crust. If
we could know the forces that produced them, we could grasp
the basic dynamic principles of the earth's development. Un-
fortunately, though the mountains have long been the sub-
ject of intensive scientific investigation, they have preserved
their secrets well. The most important of these secrets is the
secret of their birth. What forces within the earth were re-
sponsible for their formation? As of now, we do not know.
Nothing could better betray the extent of our ignorance
of the dynamic processes that have shaped the face of the
earth than this confession of ignorance. Yet, it is agreed by
geologists that no theory has so far satisfactorily explained
mountain building. Daly, for example, has referred to the
process of the folding of the rock strata, a phase of mountain
building, as "an utterly mysterious process" (7od:4i). Guten-
berg has concluded that none of the present theories will do.
He remarks that "all the forces discussed so far seem to be
insufficient to produce the formation of mountains" (194:
171), and this includes, of course, the long-exploded (but still
widely current) theory that ascribes mountains to the cooling
and shrinking of the earth. As to this, Gutenberg remarks,
". . . other scientists have pointed out that the cooling of
the earth is not sufficient to produce the major part of the
crumpling, especially since investigations of the radioactive
heat which is produced inside the earth have indicated that
8o EARTH'S SHIFTING CRUST
the cooling of the earth is less than it had been originally be-
lieved. . . ." (194:192). Bullard, reviewing the third edition
of Harold Jeffreys's basic work, The Earth, notes the absence
of progress toward solving the problem of mountain build-
ing, since the second edition twenty-five years ago (59).
Pirsson and Schuchert, the authors of a general text on geol-
ogy, conclude a section on the cause of mountain building
with the statement: "It must be admitted, therefore, that the
cause of compressive deformation in the earth's crust is one
of the great mysteries of science, and can be discussed only in
a speculative way" (345:404).
What is the nature of this problem that has so far baffled
science?
/. The Problem of Crustal Folding
It is important to take into account the fact that there are sev-
eral different kinds of mountains, and that their origins may
be ascribed to somewhat different circumstances, even though
(as we shall see) they may be related to one underlying cause.
Some mountains are caused by volcanic eruptions. These con-
sist of piles of volcanic matter. Some of the greatest moun-
tains on the earth's surface are volcanic mountains. Many
of them are found on ocean bottoms, and when they rise to
the surface they form the island chains (such as the Hawai-
ians) that are especially numerous in the Pacific. Sometimes
volcanic islands or mountains can be formed quickly, as was
the case recently in Mexico, where a large mountain,
Paricutfn, was developed in a few years to a height of several
thousand feet from a lava flow that started in a cornfield on
the level ground. Some mountains result from a vast flow of
molten rock that gathers under the crust at one spot and
domes it up. The causes of these events are unknown.
Many mountains, and even whole ranges of mountains, are
brought into existence in part by the cracking of the earth's
crust, accompanied by the tilting of the separated blocks. The
THE MOUNTAINS 8l
Sierra Nevada Mountains of California appear to have been
formed in this way. According to Daly, they represent the
tilting of a single block of the earth's crust some 600 miles
long (98:90). Some folding of the crust, however, had previ-
ously taken place. Many great chasms, extended cliff forma-
tions, and rift valleys appear to have been formed by the
cracking and drawing apart of the crust, and by the elevation
or subsidence of the different sides. The great African Rift
Valley is perhaps the best-known example of this sort of
formation; the rift of which it is a part, as we shall see below,
has recently been connected with a world-wide system of
great submarine rifts. The cause of all this cracking and
tilting is still one of the mysteries of science.
The greatest mountain systems on the earth's surface have
been formed as the result of the lateral compression and fold-
ing of the crust. Since folding is the cause of most mountain
building it must hold our particular attention. As already
suggested, science is particularly at a loss to explain the fold-
ing. A number of suggestions have been advanced, but they
are all deficient for various reasons.
A part of the public is under the impression that moun-
tains have been formed by the action of running water, wear-
ing away the stone, eroding the tablelands, and depositing
layers of sediment in the valleys and in the sea. Although it
cannot be denied that erosion has been a powerful factor in
shaping many mountains, and may have been the main factor
in shaping some of them (for example, Mt. Monadnock, in
New Hampshire, which I can see from my window as I write
these words), it cannot have been the principal cause of the
formation of our great folded mountain ranges.
Geologists who have argued in favor of this theory have
pointed out that the deposition of sediment in narrow crustal
depressions may have been a cause of the folding of the crust.
The folding could have resulted in part from the sinking of the
valley bottoms under the weight of the sediments. The proc-
ess will be found described in detail in almost any textbook
of geology. There are serious objections to it, and no geol-
82 EARTH'S SHIFTING CRUST
ogist today considers it a satisfactory explanation. One ob-
jection is that this process of folding is essentially locaL It
cannot explain the greatest mountain systems, spme of which
virtually span the globe. It cannot explain, for example, the
almost continuous line of mountain ranges that includes the
Rockies, the Andes, and the Antarctic Mountains, and which
extends for a total distance of almost half the circumference
of the earth. Neither can this theory explain the numerous
submarine mountain ranges that have, in recent years, been
discovered on the bottoms of the Atlantic, Pacific, and Arctic
Oceans. Moreover, it has been pointed out that in many cases
folding of the crust has taken place without any deposition of
sediment, and therefore must have been due to other causes.
The geologist Henry Fielding Reid remarked:
. . . There are many deeps in the ocean, such as the Virgin Islands
Deep, the Tonga Deep, and others, which appear to have sunk with-
out any material deposit of sediments. . . . (354).
For these various reasons, then, geologists have come to the
conclusion that erosion is only a secondary cause of mountain
building (345:382-84). We shall consider this again.
Another common impression, as already mentioned, is that
mountain formation has been due to the cooling and shrink-
ing of the earth. It was reasonable, perhaps, as long as the
theory of the cooling of the earth was unquestioned, to try
to explain the origin of folded mountains in this way, for, of
course, if the earth shrank in size, even only slightly, as a re-
sult of cooling, some wrinkling of the crust must be the
result. The fact that the pattern of wrinkles that would be
produced in this way (and which could be deduced fairly
clearly) bore no resemblance whatever to the patterns of the
existing mountain ranges, did not greatly diminish the cur-
rency of this theory, though it did bring about a devastating
attack upon it by one competent geologist whose views we
shall discuss below.
We have seen that there is now an impressive body of evi-
dence and opinion against the theory of a molten origin for
THE MOUNTAINS 8j
the earth. The doubts that have gathered about this assump-
tion are sufficiently serious to prevent us from basing any
theory of mountain building upon it (for no theory can
have greater probability than its own basic assumptions). But
even if this were not the case, even if the molten origin of the
earth were a demonstrated fact, still, it was pointed out
twenty-five years ago, by Clarence Button, that the shrinking
of the globe would not explain the folded mountains. Button
had two objections. First, he said that the calculated amount
of the shrinkage that could have occurred since the crust was
formed, by the reduction of temperatures, would not account
for the volume of the mountains known to have existed dur-
ing geological history. Secondly, he pointed out that the
kinds of pressures that would exist in the crust as a result of
the shrinking of the earth could not produce mountain
ranges of the existing patterns. On this point, he said:
... As regards the second objection, which, if possible, is more
cogent still, it may be remarked that the most striking features in the
facts to be explained are the long narrow tracts occupied by the belts
of plicated strata, and the approximate parallelism of their folds.
These call for the action of some great horizontal force thrusting in
one direction. Take, for example, the Appalachian system, stretching
from Maine to Georgia. Here is a great belt of parallel synclinals and
anticlinals with a persistent trend, and no rational inquirer can doubt
that they have been puckered up by some vast force acting hori-
zontally in a northwest and southeast direction. Doubtless it is the
most wonderful example of systematic plication in the world. But
there are many others that indicate the operation of the same forces
with the same broad characteristics. The particular characteristic with
which we are concerned is that in each of these folded belts the hori-
zontal force has acted wholly or almost wholly in one direction. But
the forces that would arise from a collapsing crust would act in every
direction equally. There would be no determinate direction. In short,
the process would not form long narrow belts of parallel folds. As I
have not time to discuss the hypothesis further, I dismiss it with the
remark that it is quantitatively insufficient and qualitatively inap-
plicable. It is an explanation that explains nothing that we want to
explain. . . . (122:201-02).
It is indeed astonishing to note that though a quarter of a
century has passed since this statement was made, and though
84 EARTH'S SHIFTING CRUST
leading geophysicists today sustain Button's views (194:192),
the impression is still widespread, and not merely among lay-
men, that mountains are, more or less, understandable as
the consequence of the cooling of the earth. The cause of this
inertia is, very likely, the absence of any alternative, accept-
able theory of mountain building.
In recent years many geologists have agreed with Button
that the mountains were folded by some immense force oper-
ating horizontally on the earth's crust. Furthermore, they
have come to recognize that the force or forces involved in
mountain folding acted on the earth's crust as a whole and
at the same time. Thus, one of our leading geophysicists, Br.
Walter Bucher, of Columbia, remarked:
Taken in their entirety, the orogenic [mountainous] belts are the
result of world-wide stresses that have acted on the crust as a whole.
Certainly the pattern of these belts is not what one would expect
from wholly independent, purely local changes in the crust (58:144).
The same thing was pointed out by Br. Umbgrove:
. . . But the growing amount of stratigraphic studies make it in-
creasingly evident that the terrestrial crust was subjected to a period-
ically alternating increase and decrease of compression. ... I feel
there is overwhelming evidence that the movements are the expression
of a common, world-wide, active, and deep-seated cause. . . . (430:31).
Br. Umbgrove was impressed by another characteristic of
this world-wide force. It did not act continuously. It was not
always acting to expand or squeeze sectors of the crust to fold
them into mountains. It acted only at certain times, and
then, for other periods, it was inactive. There was a sort of
periodicity to its operation. This periodicity extended also
to other aspects of the earth's geological history:
The geologist comes across periodicity in many of the pages which
he is arduously deciphering—in the sequence of the strata, for in-
stance, and their contents of former organisms. . . . He observes it
elsewhere, in the deep-seated forces that bring subsidence first in one
area and then in another ... in the intrusion of liquid melts or
"magma" rising from some deeper part of the earth's interior; in the
THE MOUNTAINS 87
ing. Joly attempted to prove that the accumulation of radio-
active heat in the earth resulted in mountain building at
intervals of 30,000,000 years (244; 235:153). Gutenberg, how-
ever, says that details of Joly's theory have been disproved
(194:158) and, moreover, that the theory includes no mecha-
nism to account for the 3o,ooo,ooo-year intervals (194:188).
It is impossible to see that the resulting upheaval of the
surface could produce mountain ranges of the patterns that
exist. Joly's theory does postulate a growing earth, but
whether the crust bursts occasionally or is continually col-
lapsing because of shrinking, it all amounts to the same
thing: neither theory meets the requirements. Attempts have
also been made to explain periodicity as the result of long-
range astronomical cycles, but they have been unsuccessful
(430:281-82). It is obviously difficult to explain mountain
building by astronomical cycles.
For some years, geologists have been looking for a moun-
tain-folding force below the earth's crust. They have been
investigating the possibility of the existence of currents in
the semiliquid layers under the crust, and speculating on the
possible effects of such currents, if they exist, on the crust
itself. It has been suggested that such currents, rising under
the crust, or sinking, might fold the crust. A sinking current,
for example, would have the effect of drawing the crust to-
gether over it, and pulling it down, forming wrinkles, in
long narrow patterns, like the mountain ranges. Calculations
have been made of the forces that could be brought to bear
upon the crust in this way. Vening Meinesz prefers this way
of accounting for mountain building:
If we examine the pattern of great geosynclines over the earth's
surface, we cannot doubt that their cause must have a world-wide
character. The geology in these belts points to horizontal compression
in the crust, at least during the later stages of their development. The
two main hypotheses suggested to explain these great phenomena are
(i) the thermal-contraction hypothesis, and (2) the hypothesis of sub-
crustal current systems of such large horizontal dimensions that, ver-
tically, they must involve at least a great part of the thickness of the
mantle and probably the whole mantle (349:319).
88 EARTH'S SHIFTING CRUST
Vening Meinesz summarizes the arguments against the
thermal-contraction hypothesis (the cooling of the earth),
and argues for the second theory. It is interesting, in passing,
to note that one of his arguments against the contraction
theory is that "In large parts of the earth's surface . . . ten-
sion seems to exist in the crust at the same time that folding
takes place elsewhere, and this fact is difficult to reconcile
with thermal contraction (giving compression) throughout
the crust. . . ." (349:320). He is here saying that the earth's
crust was being stretched in some places and compressed in
others, at the same time, which is inconsistent with the cool-
ing and contracting theory. It is, however, quite consistent
with the crust displacement hypothesis.
Now, as to the subcrustal current hypothesis, we may note
that Meinesz is assuming currents travelling for great dis-
tances horizontally, and moving in great depths of hundreds
of miles below the crust. Naturally, the movement of such
masses of rock could potentially create pressures to stagger
the imagination. Gutenberg discusses the work of many men
who are studying subcrustal currents (194:186, 191). The
chief weakness of the theory is the absence of any real evi-
dence for the existence of such currents. It is suggested, for
example, that thermal convection might account for them,
or chemical changes of state in depth might account for
them, or mechanical factors might be at work, but, mean-
while, there is no real evidence that such currents really
exist. Some geologists have claimed to have found evidence
of cyclonelike patterns in rock structures (194:188), but these
appear to have been of small magnitude; they therefore may
have been formed in small pockets of molten rock. They do
not provide reliable evidence for the existence of gigantic
crust-warping currents, such as would be required for moun-
tain building.
The problem that we are involved with here is that of the
origin of the geosyncline. Geologists refer to a downward fold
in the crust of major proportions as a geosyncline. An up-
ward fold (or arch) is a geoanticline. They are sometimes
THE MOUNTAINS 91
ments and possibly through a number of successive displace-
ments of the crust, to the formation of folded mountain
ranges.
The systematic presentation of this theory requires us to
consider the two different phases of displacement— equator-
ward and poleward— separately, for they have very different
results. We will begin with the consideration of the effects
of a displacement of a crustal sector toward the equator.
In a shift in that direction, a crustal sector is submitted
to tension (or stretching), and this tension is relieved by the
fracturing that takes place when the bursting stress exerted
on the crust has come to exceed the strength of the crust. (For
Mr. Campbell's calculations of the quantity of the bursting
stress, as compared with estimates of crustal strength, see
Chapter XI.) Until fractures appear and multiply, the crust
caijnot move over the bulge. After the fracturing permits
the movement to begin, the crustal blocks tend to draw
slightly apart. The spaces between them are immediately
filled by molten material from below.
Let us form a clear picture of this crustal stretching, from
the quantitative standpoint. It is important to estimate the
stretch per mile, if we are to visualize the results. Taking the
globe as a whole, the difference between the polar and equa-
torial diameters is about 26 miles. The circumferences,
therefore, differ by about 78 miles. If the crust were dis-
placed so far that a point at a pole was displaced to the
equator, the polar circumference would have to stretch 78
miles to fit over the equator. This would amount to about
17 feet in the mile. Since the magnitude of displacements,
however (according to evidence to be presented later), seems
to have been of the order of no more than about 30 degrees,
or one third of the distance from pole to equator, the average
stretch per mile may have amounted to five or six feet, or
one foot in a thousand.
It would be a mistake to visualize this stretching of the
crust in the equatorward-moving areas as evenly distributed
around the whole circumference of the globe. Obviously, the
g2 EARTH'S SHIFTING CRUST
real events would not correspond to this. The crust would
be under bursting stress, and this would be relieved spas-
modically, during the movement of the crust, by fractures at
the weakest points. A fracture through the crust at one point
would relieve the stress for perhaps hundreds of miles. Since
the elasticity of the crust is slight, the stretching or extension
of the crust would consist of the drawing apart, to varying
distances, of the fractured blocks. Generally speaking, the
fewer the fractures, the farther their sides would draw apart.
It would be possible that the total amount of the stretching
of the earth's circumference would be concentrated in rela-
tively few critical areas.
It must also be kept in mind that some parts of this area
being displaced toward the equator will be displaced farther
than others. The greatest displacement will occur along the
line, or meridian, drawn from the pole through the center of
mass of the icecap and so around the earth; or, if any unex-
pected factor should deflect the direction of the movement,
the greatest displacement will occur along whatever meridian
represents the direction of the movement. As I have pointed
out, at two pivot points on the equator 90 degrees away from
this meridian there will be little or no movement, and the
points in between will move proportionately to their dis-
tances from the meridian. The tension, or stretching, will be
proportional to the amount of displacement. It therefore will
be greatest along the central meridian of movement, and it
is here that Mr. Campbell expects the first major fractures
of the crust to develop.
It is important to visualize the nature of the crust on which
this tension is exerted. The crust is comparatively rigid, hav-
ing little elasticity, but it is not strong. It varies in thickness
and strength from place to place. As we shall see, it is even
now penetrated by great systems of deep fractures of unex-
plained origin. These inequalities of strength will be very
important in determining the reactions of the crust from
place to place to the tension exerted upon it; they will de-
THE MOUNTAINS 93
termine the precise locations, and to some extent the pat-
terns, of the fractures that will result.
Without attempting to anticipate a more detailed discus-
sion, to be introduced later, of the forces involved in this
fracturing of the crust, I would like to remark that the forces
required for the fracturing are by no means so great as might
be at first supposed. It is a question of relatively slight forces
exerted over considerable periods of time.
If we disregard the factors that may locally influence the
locations and sizes of fractures, a general pattern may be indi-
cated to which they will tend to conform. Mr. Campbell has
worked out this pattern schematically, and has indicated it in
Figures II, III, and IV. The reader will note that the fractures
take two directions. There are the north-south, or meridional,
fractures, which Mr. Campbell refers to as the major frac-
tures, and then there are minor fractures at right angles to
them.
Mr. Campbell anticipates that numerous major fractures
will occur parallel to each other as the crust moves. The for-
mation of very numerous minor faults at right angles to the
major faults will form a gridiron pattern of fractures. Mr.
Campbell has suggested a method for visualizing the process.
If the reader will cup his hands and place them together,
with fingertips touching and the fingers of each hand close
together (as if they lay on the surface of a sphere), and then
imagine the sphere growing, and causing the fingertips of
both hands to spread apart, and at the same time the fingers
of each hand to spread apart, he may visualize the process.
The gap between his hands will now represent a major frac-
ture, and the gaps between the fingers of each hand will
represent the minor fractures at right angles to it. The reader
will see, a little later on, how closely this projection of frac-
ture effects corresponds to the real phenomena in the earth's
crust.
Another important aspect of these fractures is shown in
Figure III. Mr. Campbell has indicated that, owing to the
changing arc of the surface as the crustal sector moves
94
EARTH'S SHIFTING CRUST
Fig. II. Mountain Building: Patterns of Fracture and Folding
The lithosphere, or crust, is represented in a future movement resulting
from the effect of the present icecap in Antarctica. Since the latter' s
center of mass is on (or near) the meridian of 96° E. Long., the crust is
represented as moving in that direction from the pole. The sector of
expansion is moving equatorward and therefore being extended. The
sector of contraction is moving toward the North Pole from the equator
and therefore being compressed.
In the sector of expansion, parallel major faults can be observed, with
minor faults at right angles. The wavy lines suggest the effects of local
differences in crustal strength. The pattern of the fractures is indicated,
but not their number; a very large number of meridional fractures
might be formed, while the minor fractures would be even more
numerous.
In the sector of contraction, crustal folding is shown only schemat-
ically. It is represented as if all the folding is taking place along one
meridian, although in reality there would probably be many parallel
zones of mountain folding at considerable distances from each other.
Campbell indicates that this movement will be accompanied by frac-
turing of the crust, with faults running at right angles to the main axes
of the folds. The third axis, which runs through the equator, is consid-
ered to be the axis on which the crust turns. The points directly at the
two ends of this axis do not move.
THE MOUNTAINS
95
POSITION OF
UTH05PHERE
IF NOT PUUEt>
DOWN BY GRAVITY
NORTH POLE
Fig. III. Vertical View of the Earth with Cross Section at 96° E. Long.
This figure illustrates a number of simultaneous effects of displacement.
The upper right-hand quadrant shows a sector of the crust displaced
toward the equator. Here the lessening arc of the surface will cause
faults to open from the bottom. The lower right-hand quadrant shows a
sector of the crust displaced toward a pole. Here the increasing arc of
the surface results in faults opening from the top. The lower left-hand
quadrant, which is a vertical view of a sector moving equator-ward, shows
major meridional faults, which have opened from the bottom. The
upper left-hand quadrant, which is a vertical view of a sector displaced
poleward, shows meridional faults opening from the top.
The reader should visualize the left-hand quadrants as if looking
straight down on the earth at the point where the central meridian of
displacement (96° £. Long, in this case) crosses the equator.
NOTE: In this and other drawings the South Pole has been shown at the
top, reversing the usual position. This has been done for reasons of con-
venience and because our theory has been developed with the Antarctic
icecap as the center of attention. In actuality, there is no such thing as
"up" or "down" in space. The North Pole is usually shown at the top,
but this is merely a convention of cartographers.
EARTH'S SHIFTING CRUST
CQUVTORtAt -
Fig. IV. Patterns of Fracture
This figure indicates schematically the mechanics of faulting and folding
in a displacement of the crust. It is suggested, for purposes of illustra-
tion only, that all effects are concentrated on the meridian of maximum
crust displacement. Therefore, only one major meridional fault is shown
in the upper hemisphere, which is moving toward the equator. Dotted
lines indicate other faults opening from the bottom of the lithosphere,
or crust, as the arc of the surface diminishes.
Across the equator, where the surface is moving toward the pole, and
compression is resulting, the continuation of the major expansion fault
is shown as a pressure ridge, which may later become the main axis of
a mountain range. Again, for purposes of illustration only, it is assumed
that all folding will take place along the meridian of maximum dis-
placement. If the major fault is filled with molten magma, and the
magma solidifies, then this intruded matter, which has expanded the
crust, must add to the folding in the lower hemisphere, which is moving
toward a pole.
In the lower hemisphere the unbroken lines indicate the fractures
opening from the top, as the arc of the surface increases.
equatorward, the fractures will tend to open from the bot-
tom. This would, of course, favor the intrusion into them of
magma from below, and, accordingly, Mr. Campbell shows
them filled up (in black). At the same time, as the reader may
THEMOUNTAINS 97
see, fractures in areas moving poleward would tend to open
from the top. These might be less likely to reach sources of
molten rock; accordingly, they are not shown filled up.
Whether these fractures would or would not fill up (and
perhaps the probabilities are that they would), the configura-
tion of the resulting solidified veins in the rocks would be
very different from that in fractures that had opened from
the bottom. Campbell has suggested that this way of explain-
ing existing fracture patterns in the crust could be an aid
in prospecting for ores, most of which occur in such veins.
It would be a question of ascertaining, for the general region,
whether the veins being investigated were part of either a
poleward type or equatorward type of pattern, and from this
it might be possible to deduce whether the vein was to peter
out or not. Campbell believes that the hypothesis provides
numerous possibilities for the exploration of the crust, some
of which may prove eventually to be of commercial value.
The time element is essential to visualizing the general
process of a displacement. Some concept of the probable
speed of the displacement is required. A basis for such an
estimate is provided by evidence that will be fully considered
later, but I may here anticipate by saying that displacements
may have required periods of from 10,000 to 20,000 years.
This means that this amount of time would be available for
the creation of the system of fractures we are considering. It
means, for example, that a single major fracture, which might
involve, let us say, the pulling apart of the crust to a distance
of several miles and the filling up of the crack with molten
material from below, might be formed over a period of
several thousand years, during which time there might be
spasmodically renewed earthquake fracturing and volcanic
effects, interrupted by periods of quiet. It is obvious that the
amount of time available for the work of extension and frac-
turing of the crust is sufficient to permit the process to com-
plete itself without undue or incredible violence.
We must now consider a question that relates to mountain
building, and at the same time involves another of the major
98 EARTH'S SHIFTING CRUST
unsolved problems of geology. It is connected with our phase
of equatorward crust displacement. It has to do with the
filling of the fractures by molten magma from below. Camp-
bell considers that this filling of the fractures is the first step
in mountain building, or at least in the formation of a
geosyncline. Obviously, it is possible to start the process at
other points; this is therefore only a matter of convenience,
and for the purpose of drawing a clear picture of the process
for the reader. But Mr. Campbell points out that the process
of the filling of the cracks, and the later solidification of the
intruded material, adds extension to the crust; there is now
more surface. When, in future shifts of the crust, this area
passes over the equator toward a pole, or moves poleward
from where it is, the extended surface has to yield to the
resulting compression by folding more than it would have
had to do had there been no molten intrusions in the first
place. It is, therefore, reasonable to call this the first step in
mountain building, although there is as yet no folding, and
no uplift of the rock strata.
But this question of molten intrusions into the crust raises
another sore point. It has been, until now, a very difficult
thing to explain the rise of molten matter into the crust.
Geologists have speculated as to what force could have shot
up the molten matter that formed the innumerable "dikes"
and "sills," as the resulting veins are called. They have not
been able to agree upon the question. No reasonable ex-
planation of these millions of magmatic invasions of the crust
has been found.
Of course, it is realized that the crust of the earth is, in a
sense, a floating crust. The materials of which it is composed
are lighter, it is assumed, than the materials below, and are
solid, as compared with the plastic or viscous state of the
underlying layers. The crust can be thought of as floating
in hydrostatic balance in the semiliquid lower layer. This is
generally understood among geologists. It follows logically
from this that, if two or more blocks of the crust got sepa-
rated with cracks between them, the "molten" material
THEMOUNTAINS 99
would rise in the crack, and the blocks would sink, until the
cracks weie filled up far enough to establish hydrostatic bal-
ance. But this did not solve the problem; it did not help
because nobody could imagine what could produce the neces-
sary pulling apart of the blocks.
For those who like to see complicated problems made sim-
ple, Mr. Campbell's presentation of this matter is worth
considering. He suggests that the concept of a great sector
of the crust being stretched, and thereby fractured in in-
numerable places at one time, permits a comparison to be
made with an ice sheet, which is floating on water, and which
undergoes fracturing. Just as the individual pieces of the ice
floe sink, until they have displaced their weight in water,
and the water rises in the cracks between the pieces, so he
visualizes the behavior of the crust during its displacement
equatorward. He sees this as the explanation of the fact that
although the crust is shot through with igneous invasions of
all sorts, these are hardly ever known to reach the surface of
the earth. He compares the behavior of the crust during dis-
placement with the behavior of ice as follows:
... As a matter of fact the lithosphere (or crust) can be likened to
ice floating on water, a solid and lighter form of a substance floating
in a liquid and heavier form of a similar substance. The solid and
lighter substance sinks in the heavier and liquid substance until it
displaces its own weight in the heavier and liquid substance and then
floats with its surplus bulk above the surface of the heavier liquid,
which in the case of ice would be one tenth of its bulk. To put it
another way, if you were out on a lake where the ice was ten inches
thick, and you were to bore a hole through the ice to the water, the
water would rise in the hole to within one inch of the surface of the
ice and remain there. Now, that is exactly what happens to the litho-
sphere. It sinks into the asthenosphere (or subcrustal layer) until it
displaces its own weight of the substance of the asthenosphere and a
state of equilibrium is reached. That will bring the substance of the
asthenosphere far up into the lithosphere, wherever it finds an open-
ing or a fault that reaches all the way to the bottom of the litho-
sphere (66).
Purely for purposes of illustration, and not as an accurate
100 EARTH S SHIFTING CRUST
picture of the facts, Mr. Campbell has made a very rough
calculation, as follows:
Assuming that the lithosphere is composed of granite that has a
weight of 166 pounds to the cubic foot, and the asthenosphere con-
sists of soapstone with a weight of 169 pounds per cubic foot, the
lithosphere being three pounds lighter per cubic foot than the
asthenosphere, it would float in the heavier asthenosphere leaving
1.775% of its volume above the surface of the asthenosphere, and as
the lithosphere is assumed to be forty miles deep in this case, then
1.755% of forty miles would be .71% of a mile above the top of the
asthenosphere. That is, the soapstone molten asthenosphere would
rise up into the fault to within three quarters of a mile of the surface
of the earth. . . . (66).
Summarizing his general thoughts regarding the effects of
an equatorward displacement of a crustal sector, and the
hydrostatic balance of the crust itself, Mr. Campbell has
remarked:
I think you should stress this point, for, while the geophysicists
have seen faults in the earth's crust, and have seen many of these
faults that they knew had been filled up from below, they didn't have
any logical solution of what caused the faults, nor did they connect
the faults with the formation of our mountains (66).
5. The Effects of Poleward Displacement
In the poleward displacement of sectors of the crust, com-
pression, instead of extension, would be the rule. The mag-
nitudes and the distribution of forces, and the time element,
would, of course, be the same. Otherwise, the effects would
be very different.
We should have, in the first place, some folding of the
rock strata. As with the fractures, the precise locations of the
rock foldings, their number, and their magnitudes would be
controlled by the amount of the displacement locally, the
local variations of crustal strength (which would be less
where geosynclines already existed), and the distances of the
areas concerned from the central meridian of movement.
THE MOUNTAINS 1O1
The amount of the folding would be increased as the result
of any previous process of extension of that area of the crust
in any previous displacement.
The elastic properties of the crust would probably be of
much greater importance in this compressive phase than in
the extensive phase of a displacement. This is because com-
pression could lead to flexing or bending of the crust, to a
slight degree, without a permanent change of shape. It might
be possible to bend or flex the crust slightly, and hold it so
for thousands of years, without fracture or folding of the
rock strata, or even without much plastic flow of the ma-
terials. This would mean no permanent change in the con-
formation of the surface. A compressive tension might be
exerted for thousands of years, causing a flexing, and then
be relaxed, permitting the crust to return to its original
shape. It may be supposed that in areas sufficiently removed
from the meridian of maximum displacement, the com-
pressive tensions on the crust might be contained by its ten-
sile strength, and the crust might yield elastically, without
deformation. If this occurred, however, the total amount of
the compression for the whole circumference of the globe
would probably be concentrated at comparatively few points,
where the compressive stresses happened to be in excess of
the strength of the crust; here there would be a considerable
amount of folding of the rock strata. It is obvious, also, that
these points would tend to coincide with existing geosyn-
clines, which would naturally represent comparatively weak
zones, where the crust would be less able to withstand the
horizontal stress.
Mr. Campbell suggests that in an area displaced poleward,
no fewer than four pressures will be operating simul-
taneously on the crust. There will be, in the first place, two
pressures developing from opposite directions toward the
meridian of displacement. These will arise because of the
diminishing circumference. Two other pressures will simul-
taneously develop at right angles to these, as the result of the
reduced radius. Since the radius is only one sixth of the cir-
IDS EARTH'S SHIFTING CRUST
cumference, the forces will be in proportion; the folds due
to the first compression will tend to be six times as long (and
accentuated) as those due to the second compression. The
former may ultimately correspond with the long axes of
the mountain ranges, and the latter to their radial axes. The
long, narrow, folded tracts referred to by Button are thus
explained.
In Figure II Mr. Campbell has suggested an idealized rep-
resentation of the formation of a mountain chain by a dis-
placement of the crust. The reader will note the long major
axis, and the shorter radial axes. That this is a fairly close
approximation to the patterns of existing mountain ranges
is obvious; however, a number of modifying factors must be
recognized. In the first place, we do not contemplate that a
mountain range can be completed in the course of one move-
ment of the crust. It is quite obvious, from the quantitative
considerations already mentioned, that a single displacement
could cause comparatively little folding, even if, as the result
of elastic yielding, most of the folding was concentrated in a
few areas. It is certain that many displacements would be re-
quired to make a large mountain range, and since successive
displacements will not necessarily occur in the same direc-
tions on the earth's surface, the resulting patterns might
rarely conform to the idealized pattern. And yet, if most of
the folding in one displacement happened to be concen-
trated in one area, and if one or more successive displace-
ments happened to concentrate folding in the same area, a
mountain range might come into existence in a compara-
tively short period of two or three hundred thousand years.
We will return to this chronological aspect again.
It should not be thought that Mr. Campbell is in disagree-
ment with Button's statement, quoted above, that the com-
pressive mountain-folding forces have acted in one direction
only on the earth's surface. This would be a misunderstand-
ing of the case. The laws of physics require the operation of
equal and opposite forces for the production of effects. A
compression is the result of two equal and opposite pressures.
THE MOUNTAINS
There is still one definite direction, such as northeast-south-
west, in which the compression operates on the crust.
4. The Mountain-Building Force
An apparently formidable objection that has been raised to
this theory of mountain formation is that the force pro-
vided by the icecaps cannot be sufficient. When you look at
the towering summits of the Sierras from your speeding
plane, and your eye takes in the numberless peaks fading
away into the far horizon, you are impressed by the thought
of the enormous force that must have been required to raise
this great chain of mountains. How could all this have been
the result of a gentle pressure applied to the crust of the
earth by distant icecaps?
Campbell has shown that the apparent discrepancy be-
tween the cause and the effect, here, is the result of a misap-
prehension as to the identity of the actual force responsible
for the mountain folding. His calculations (given and dis-
cussed in Chapter XII) show that the thrust transmitted to
the lithosphere by the icecap is of the right order of magni-
tude to bring about the fracturing of the crust. The icecap
may therefore be responsible for the movement of the crust;
yet it is not the force directly responsible for the folding of
the mountains. The latter is a much greater force. Mr. Camp-
bell shows that the mountain-folding force is none other than
the force of gravity itself. He suggests that the icecap per-
forms the function merely of sliding the crust horizontally
to a place where the force of gravity can act upon it. When
an area is moved toward a pole, where the radii of the earth
are shorter, circumference is shorter, and surface required is
less, there is a surplus of surface, and this, being pulled down
by gravity, must fold. From this point of view, it appears that
the mountains are not pushed up at all, and therefore, no
lifting force is required; instead, it is the surface of the earth
that is pulled down, by gravity, nearer to the earth's center,
104 EARTH'S SHIFTING CRUST
as a sector of the crust approaches a pole. Where this hap-
pens, the surplus surface must fold. Thus it is the force of
gravity, over a large area, that folds the crust in a small area.
It may help the reader to grasp this idea if he will visualize
a flat area on the equator which, in process of being displaced
with the crust as far as a pole, has been folded enough to pro-
duce mountains six miles high. Now, actually, the peaks of
those mountains are no farther from the center of the earth
than the flat area was at the equator. Their altitude, with
reference to the earth's center, is unchanged. What has
changed altitude, however, is the rest of the surface, outside
the mountain chain. That has been pulled down six miles.
What pulled it down, obviously, was the force of gravity, and
the reason it was pulled down was that it was first shifted
horizontally to a place where gravity could act upon it.
Here, then, is the answer to the long-standing enigma of
the source of the energy for mountain folding. The moun-
tains are not lifted up at all; the surface is pulled down, the
force of gravity does the pulling, and folding results where
there happens to be excess of surface.
JF. Existing Fracture Systems as Evidence for the Theory
It is ordinarily considered a strong argument in favor of
a hypothesis if it enables one to anticipate the discovery of
phenomena. Campbell has shown that the theory of displace-
ments of the earth's crust calls for the existence of great sys-
tems of parallel fractures, intersected by other fractures at
right angles to them. It was some time after Mr. Campbell
began to consider this matter, and quite independently of
him, that I became aware of the fact that such fracture pat-
terns do, in fact, extend over the whole face of the globe,
and that geologists are in agreement that their origin is un-
explained. Many years ago Hobbs pointed out that they
must have been the result of the operation of some world-
wide force:
THE MOUNTAINS 105
The recognition within the fracture complex of the earth's outer
shell of a unique and relatively simple pattern, common to at least
a large portion of the surface, obscured though it may be in local dis-
tricts through the superimposition of more or less disorderly fracture
complexes, must be regarded as of the most fundamental importance.
It points inevitably to the conclusion that more or less uniform con-
ditions of stress and strain have been common to probably the earth's
entire outer shell (217:163).
As I have pointed out, Mr. Campbell's projected pattern
of fractures is a sort of gridiron, with major fractures paral-
leling the meridians, and minor fractures at right angles to
them. In the actual earth's surface, however, there are two
such patterns. One of them consists of north-south fractures
paralleling the meridians, intersected by east-west fractures
paralleling the equator. The second gridiron is diagonal to
the first; the lines run northeast-southwest, and northwest-
southeast. As to why there should be two such distinct frac-
ture complexes in the crust, I shall have more to say later on.
Hobbs insists that the existence of these world-wide patterns
points to a cause acting globally; they could not have been
the result of local causes; the force causing the fracturing
must have acted simultaneously, so to speak, over a great
part of the whole surface of the earth:
. . . The results of this correlation possess considerable significance
inasmuch as it is clear that over quite an appreciable fraction of the
earth's surface, the main lines of fracture betray evidence of common
origin. . . . (218:15).
The fracturing of the crust under the operation of some
global force has been accompanied by much tilting and rela-
tive movement of blocks of considerable size, resulting in the
alteration of topographic features. One of the earlier geolo-
gists, Lapworth, remarked with considerable truth, though
also with some exaggeration, that
On the surface of the globe this double set of longitudinal and
transverse waves is everywhere apparent. They account for the de-
tailed disposition of our lands, and our waters, for our present coastal
forms, for the direction, length and disposition of our mountain
ranges and plains and lakes (430:296).
io6 EARTH'S SHIFTING CRUST
It is clear, I think, from what has already been said, that
Lapworth was in error in ascribing the folded mountains to
the effects of fracturing alone. However, it may well be that
formation of block mountains, such as the Sierra Nevadas,
can be accounted for in this way. Innumerable other features
of the crust have been formed or obviously much affected
by the fracture patterns. Hobbs, for example, has maps of
river systems in Connecticut and Ontario, showing how
closely the rivers and their tributaries follow the lines of the
fracture systems (216:226). Many river beds, many submarine
canyons, were never created by subaerial erosion; they were,
instead, the results of deep fractures in the crust, later occu-
pied by rivers or by the sea. On the land erosion no doubt
often, if not usually, completed the shaping of the valleys,
while turbidity currents may have created or deepened can-
yons in the unconsolidated materials of the ocean bottom
037> 139* M0)-
A succession of theories to account for the world-wide or
"planetary" fracture patterns has been developed and re-
jected. As soon as it became clear that these patterns could
not be explained as the result of local forces, the problem
was recognized as very formidable. Sonder, a Swiss geologist,
attempted to explain them as the result of a difference in the
compressibility (or elasticity) of the rocks of the continents
as compared with those under the oceans. But Umbgrove
pointed out that this would call for independent fracture
systems for each of the continents, whereas existing fracture
patterns extend to several continents (430:300-01).
The Dutch geologist Vening Meinesz suggested that the
fracture patterns could be explained mathematically by a
displacement of the crust of the earth. He postulated one
displacement about 300,000,000 years ago, through about 70°
of latitude (194:204^. Umbgrove rejected this theory be-
cause he saw that there were many features of the earth's sur-
face that could not be explained by the particular displace-
ment suggested by Vening Meinesz. This is not at all
remarkable, since it is quite impossible to see how any one
THE MOUNTAINS 107
displacement, and particularly one 300,000,000 years ago,
can be made to explain most of the earth's present topo-
graphic features. Umbgrove was justified in rejecting the
Vening Meinesz theory, but he admitted that this left him
with no explanation at all. "... On the other hand, it means
that the origin of both lineament systems remains an un-
solved problem" (430:307).
Some writers have suggested that the two fracture systems
originated at different times, and this is a very important
point. Umbgrove says:
It is a rather widespread belief that the origin of faults with a cer-
tain strike dates from a special period, whereas faults with a markedly
different strike would date from another well-defined period. In cer-
tain areas this conviction is founded upon sound arguments. . . .
(430:298).
He continues:
Some authors, however, have doubtless overrated the relation be-
tween the direction and the time of origin of a fault system. As a
typical example, I may mention Philipp, who once advanced the
opinion that the direction of the principal fault lines of northwestern
Europe changed from W. and W.N.W. in the Upper Jurassic toward
N. or N.N.E. in the Oligocene, and thence E.N.E. in the upper
Tertiary and Pleistocene. He added the hypothesis that their rotation
could have been caused by a large displacement of the poles. In the
meantime it has been shown that some faults with a meridional strike
date from much older periods. Moreover, large and well-defined
faults with a N.N.W. direction dating at least from the Upper Paleo-
zoic appear to have been of paramount influence in the structural
history of the Netherlands. Therefore Philipp's hypothesis has to be
abandoned because it is inconsistent with well-established facts (430:
298).
Abandoned much too soon! The reader can easily see that
the objections Umbgrove raises to Philipp's theory are re-
moved by the present theory of crust displacements. With
this assumption, it would be inevitable that, in the long his-
tory of the globe, the poles would often be found in about
the same situations. If the strikes of the fault systems are
related to the positions of the poles, those of later periods
io8 EARTH'S SHIFTING CRUST
would often coincide approximately with those of earlier
periods.
We find in this very fact the answer to another of the mys-
teries of geology, the so-called "rejuvenation" of similar fea-
tures in the same geographical situations at various times.
The term "rejuvenation" is a commonplace of geological
literature, and is especially emphasized by Umbgrove. He
is puzzled by the fact that old geological features have re-
peatedly been called back to life. It seems that this renewal
of old topographies may be explained by the accidental re-
turn of the poles to approximately the same places.
There is nothing remarkable about the fact that only two
world-wide fracture systems can now be recognized in the
crust. If each successive displacement produced a new grid-
iron pattern of fractures and resulting surface features, it
must, in addition, have disrupted the evidence of previous
patterns. In a long series of displacements, the older frac-
ture patterns must soon be reduced to an indistinguishable
jumble. It is probable that the two systems now recognizable
date only from the last two displacements of the crust (to be
discussed later), even though many of the fractures and indi-
vidual topographic features now coinciding with these sys-
tems may date from remote periods.
It is not true, of course, that in one displacement of the
crust all fractures all over the earth will form a single rec-
tilinear pattern. This can be made clear from an example.
Let us suppose (as we shall in Chapter VII) that North Amer-
ica was moved directly southward at the end of the last ice
age. Campbell has suggested that major fractures would run
north and south (meridionally) and minor fractures east and
west, and this would be true of the whole Western Hemi-
sphere, which was, presumably, moved southward, and of
the opposite side of the earth, which was equally displaced
northward. But what about Europe? If, before the last dis-
placement, the pole was situated in or near Hudson Bay, it
seems that the last displacement must have created diagonal
and not meridional fractures in Europe, for the reason that
THE MOUNTAINS
Europe was nowhere near the meridian of displacement.
Thus, in one given displacement, a meridional fracture pat-
tern will be created near the meridian of displacement, a
diagonal fracture pattern in very large areas approximately
4.5 degrees from this meridian, and, of course, no fracture
pattern in the ''pivot" areas, 90 degrees from the meridian of
displacement, where no displacement will occur.
Lately, the oceanographic research work under the direc-
tion of Ewing has resulted in tracing a globe-encircling crack
in the bottoms of the Atlantic, Indian, and Pacific Oceans,
and has connected it with the Great Rift Valley in Africa.
The pattern that has been traced out is about 40,000 miles
long; it is reported that there is seismic activity at present
along the whole length of the crack, suggesting recent dis-
turbance of the area and a still-continuing process. The
crack appears to average two miles in depth and twenty miles
in width. The fact that it is connected with the Rift Valley
in Africa, that it bisects Iceland, and apparently invades
Siberia, indicates that it is not a phenomenon of ocean ba-
sins only. It is, on the contrary, clearly a global phenomenon.
The Columbia Research News, published by Columbia Uni-
versity, in its issue of March, 1957, described the discovery
thus:
In January, Columbia University geologists announced the dis-
covery of a world-wide rift believed to have been caused by the pull-
ing apart of the earth's crust. The big rift traverses the floors of all
the oceans and comes briefly to shore on three continents in a system
of apparently continuous lines . . . 45,000 miles long.
Throughout its vast length the world-wide rift seems to be remark-
ably uniform in shape, consisting of a central valley or trench aver-
aging 20 to 25 miles in width and flanked on either side by 75 mile-
wide belts of jagged mountains rising a mile or two above the valley.
The peaks of the highest mountains in the system are from 3,600 to
7,200 feet below the ocean's surface while the long undersea stretches
of the rift valley itself lie from two to four miles down. In addition
to being marked by its topography, the globe-circling formation is
the source of shallow earthquakes that are still going on along its
entire length— an indication that, if the rift is due to a pulling apart
of the earth's crust, the geological feature is a young and growing one.
110 EARTH S SHIFTING CRUST
What could be the cause of such a pulling apart of the
crust? Surely not a shrinking and cooling of the earth. It is
also very unlikely, it will be admitted, that the earth could
be growing fast enough to produce this split and the accom-
panying geological instability. On the other hand, a displace-
ment of the crust, or rather a series of them, may explain the
facts. It even appears that here, in this system of profound
cracks in the crust, we have evidence of the existence of zones
of crustal weakness along which, perhaps time and again, the
splits have occurred that have permitted the displacement of
the crust, and at the same time have relieved some of the
resulting tension and thereby limited the tectonic conse-
quences of the displacements so far as other areas of the
earth's surface are concerned.
To return briefly to the question of block mountains, Mr.
Campbell has a further suggestion as to the way in which
compression in a poleward displacement, and subsequent
fracturing, may combine to cause them. One of the problems
that awaits solution in geology is the cause of the widespread
doming and basining of the crust that occurs from place to
place. The domes are sometimes of considerable extent. Ex-
amples of basins include the Gulf of Mexico and the Caspian
and Black Seas. Campbell points out that if an area is dis-
placed poleward, and is thereby subjected to four compres-
sions, as already mentioned, limited areas will be entrapped
by these compressions, and doming must result; conversely,
in areas moved equatorward the reverse must occur, and
larger or smaller basins will tend to be produced.
A block mountain might tend to be produced, Mr. Camp-
bell thinks, if a major fault should bisect a domed-up area.
This would create the possibility that the abutting rock sec-
tions of one half of the dome might give way, allowing half
the dome to collapse, and pushing subcrustal viscous or plas-
tic rock under the other half of the dome, thus rendering
the latter permanent. This effect, however, would depend
upon many local circumstances.
THE MOUNTAINS 111
PART II. Volcanism and Other Questions
In the preceding part of this chapter we have sketched the
principal problems that are basic to the formation of the
folded mountains and block mountains, and have examined
the planetary fracture systems in the light of Campbell's
mechanism for crust displacement. There are, however, a
number of other aspects of this general problem that must
now engage our attention. We must consider, in turn, the
remarkable phenomena of volcanism, in their relationship to
crust displacement. In connection with the creation of vol-
canic mountains we must consider briefly the question of the
origin of the heat of the earth, an unsolved problem of great
interest. We must then examine the relationship of crust
displacement and mountain building to the question of
changes in the sea level. Finally, we must consider the prob-
lem of the chronology of mountain building.
6. Volcanism
We have seen that one kind of mountain is the volcanic
mountain. Volcanic phenomena cover a wide range; all of
these must be considered in order to see how far they can be
related to a general cause. The phenomena that need ex-
plaining include volcanic eruptions, the creation (sometimes
rapid) of volcanic mountains on land or in the sea, the gene-
sis of volcanic island arcs, and last but not least the vast lava
flows or lava floods that have at times in the past inundated
great areas of the earth's surface.
Since volcanoes occur frequently, and are the most
dramatic manifestations of volcanism, they have been thor-
oughly studied, and a whole literature has been devoted to
them. It is astonishing, therefore, that neither the causes of
volcanoes nor the present distribution of volcanic zones on
112 EARTH'S SHIFTING CRUST
the earth's surface has as yet received an acceptable explana-
tion. As in the case of other unsolved problems, the absence
of certainty has led to a multiplicity of theories. Jaggar, one
of the best field observers of volcanoes, refers to the two
leading theories thus:
It would be hard to imagine any more completely different ex-
planations for the same phenomenon than is R. A. Daly's doctrine of
the causes of volcanic action, as compared with the crystallization
theory of A. L. Day (235:150).
Dr. A. L. Day was formerly director of the Geophysical
Laboratory in Washington; his theory is based upon geo-
physical experiments conducted in the laboratory. He ob-
served that the crystallization of rock from the molten state
resulted in some increase in volume. He assumed that the
whole crust was once molten, and that as it cooled it contin-
ued to contain, here and there, comparatively small pockets
of molten rock. When such pockets of molten rock finally
were cooled to the crystallization point, then expansion
would occur, and great pressures would be set up, which
might lead to eruption at the surface. This theory is based
upon the assumption of the molten origin of the earth, and
carries with it the corollary that volcanic eruptions are essen-
tially local phenomena. Dr. Day insisted that volcanoes were
not connected with a molten layer under the crust, and were
not related to events occurring over large areas.
Professor R. A. Daly based his opposed theory on his ob-
servations of the field evidence of geology. He insisted that
only the assumption of a molten layer under the crust could
account for the countless facts of igneous geology. His theory
is reconcilable either with the assumption of the molten ori-
gin of the globe or with the theory of a growing and heating
earth.
Jaggar objects to Day's view that volcanoes are purely lo-
cal. He says:
There is some reason to think that a very long crack in the bottom
of the Pacific Ocean, with interruptions by very deep water, extends
THE MOUNTAINS 11$
all the way from New Zealand to Hawaii, because there are striking
sympathies of eruptive data between the volcanoes of New Zealand,
Tonga, Samoa and Hawaii (235:23).
He lists a number of eruptions with their dates to show their
intimate connection. In particular he mentions the eruption
of August 31, 1886, on the island of Niuafoo, Polynesia:
. . . Only two months before, Tarawere Volcano was erupted dis-
astrously in New Zealand, indicating volcanic sympathy between two
craters hundreds of miles apart on the same general rift in the earth's
crust (235:95).
These observations imply that a connection may exist, at
least in some cases, between volcanoes at great distances from
each other, because of their being located along the same
crack in the earth's crust. This implies a connection between
the deep fracturing of the earth's crust and volcanism. We
have seen that Columbia scientists have just discovered a
vast connected system of rift valleys, or cracks in the crust,
extending over the surface of the whole planet, and associ-
ated at the present time with constant seismic disturbances.
Jaggar makes it clear that volcanic eruptions, as well as earth-
quakes, may be associated with such rifts. Since the crust is
relatively thin, it is reasonable to suppose that the molten
rock erupting in volcanoes at great distances from each other
must come from below the crust, and that it is not created
by any processes occurring within the crust itself. All this is
confirmation of Daly's position.
Another theory of volcanic action that should be men-
tioned briefly is that associated with the name of W. H.
Hobbs. It was his view that volcanic action could result from
horizontal pressure arching up a sector of the crust. This is
based on the fact that if a rock that is too hot to crystallize at
normal pressures is subjected to great pressure, it may take
the solid state. Subsequently, the release of the pressure is
all that is required to restore the rock to its liquid con-
dition. In the earth's crust considerable amounts of rock
may be held in the solid state by the pressure of overlying
strata. Then, if horizontal pressure arches the crust, the
ii4 EARTH'S SHIFTING CRUST
pressure on the rock below will be relieved, and the rock
will resume a liquid state. If the arching results in cracking
at the surface, or in sufficient lateral squeezing of the liquid
pockets, eruption may take place. This effect may account for
the vast masses of igneous rock that are found associated with
the folded mountain ranges (215:58), but it is necessary to
ask the question, What causes the arching of the crust? Ob-
viously, volcanism, according to this theory, must be traced
to the cause of the arching. Hobbs's theory is not very satis-
factory because he cannot explain the arching.
It is clear that volcanism might occur as the result either
of the process imagined by Day or of that imagined by Hobbs,
for several different causes might produce liquid pockets in
the crust. But it is equally clear that neither they nor Daly
has advanced a theory to account for volcanoes, volcanic
zones, plateau basalts, and volcanic mountains. Einstein,
when he first received some material outlining the theory
proposed in this book, wrote me that it was the only theory
he had ever seen that could explain the volcanic zones (128).
These, of course, can be explained as zones of fracture (such
as the rift valleys just mentioned) resulting from crust dis-
placements.
7. The Volcanic Island Arcs
Campbell has suggested an explanation for the formation
of the volcanic island arcs, so many of which are found in
the Pacific, and which consist of chains of volcanic moun-
tains in the sea. He shows not only how our theory of crust
displacement may account for the formation of these vol-
canic mountains but also how it may account for their oc-
currence in graceful curves:
As a sector of the lithosphere, or crust, moves toward the equator,
the motion is fastest and the tension is greatest on the meridian of
movement, and great north-south faults will open up, beginning
there and spreading east and west. At the same time transverse faults
THE MOUNTAINS 117
of the earth. Smart, for example, is of the opinion that radio-
activity cannot produce heat in the earth as fast as it can be
radiated through the crust into outer space (396:62).
Some of the essential facts in any consideration of the
question of the origin of the earth's heat may be summarized
as follows. First, we know nothing of the temperature of
the earth's interior. We can only guess at it. We have made
deductions concerning it from the heat gradient observed
in the world's deepest mines. As we descend to a depth of
about four miles, the heat steadily increases (194:139). We
have assumed that the increase of heat continues at the same
rate farther down, perhaps all the way to the earth's center,
but there are a number of facts that throw doubt on this
assumption. For one thing, Daly thought he saw evidence
that the heat gradient differs in America and in Europe,
being somewhat steeper in North America (194:139). This
would imply that there is more heat in the earth's crust in
North America than there is in Europe. Benfield produced
much more evidence of variations in heat from place to
place (28) which are difficult to reconcile with a uniform heat
gradient in the earth.
Geophysicists have now concluded that the earth's heat
originates in the crust itself, and does not come from the
deep interior (194:157). The considerations on which this
conclusion is based are too technical for discussion here, but
there seems to be no reason to doubt their validity. This con-
clusion is, of course, irreconcilable with any assumption that
the earth's heat is simply the remnant of far higher tempera-
tures prevailing in a molten stage.
A matter of great importance for the general problem is
the rate at which heat migrates through the crust, and is
dissipated into outer space. Geophysicists have determined
that the rate of heat migration through the crust is extremely
slow. Jeffreys calculated that it would take 130,000,000 years
to cool a column of sedimentary rock 7 miles below the
earth's surface by 250° C. (241:136). As a result of this,
the climate of the earth's surface is determined entirely by the
n8 EARTH'S SHIFTING CRUST
radiant heat of the sun, and is uninfluenced by heat from
within the earth. We shall have to consider the bearing of
this on another well-known fact, which is that earthquakes,
and other movements within the crust, are known to produce
heat as a consequence of friction between the moving crustal
blocks (194:158). Then, earthquakes are most frequent in
areas where there are distortions of the gravitational balance
of the crust, while heat gradients are steeper in such areas
(194:141). This indicates that any factor causing such distor-
tions may be a factor in the production of the earth's heat.
Considering these facts, what are the implications, so far
as the earth's heat is concerned, of a displacement of the
earth's crust? Can there be any doubt that a crust moving
slowly over a period of a good many thousand years must
generate an immense quantity of heat within itself? There
can be no doubt of this. The widespread fracturing, the fric-
tion between crustal blocks, resulting from the increased
number of earthquakes, could have no other result. More-
over, Frankland has pointed out that friction between the
crust and the layer over which it moves must produce heat,
which may itself facilitate the displacement (168).
The heat thus produced would migrate both inwards into
the body of the earth and outwards into space. But, since the
rate of dissipation of this heat is so extremely slow, it follows
that displacements at relatively short intervals might pro-
duce heat more rapidly than it could be dissipated. Over
hundreds of millions of years slight increments of heat from
this source may have accumulated to produce the earth's
present temperature. The assumption of frequent crust dis-
placement thus suggests a third possible source of the earth's
heat, in addition to those mentioned by Gutenberg.
If it is true, as Daly thought, that the heat gradient is
steeper in North America than in Europe, this fact serves
as additional confirmation of a displacement of the earth's
crust at the end of the Pleistocene. Later I shall present evi-
dence to suggest that the crust moved at that time in such
a direction as to bring North America down from the pole
THE MOUNTAINS
to its present latitude. If this occurred, it meant a displace-
ment of about 2,000 miles for eastern North America, but
of only about 500 miles for western Europe. Quite obviously,
crust adjustments and resulting friction must be propor-
tional to the amount of the displacement, and therefore fric-
tion and resulting heat could be expected to be somewhat
greater in America.
To return, now, to our plateau basalts, we may observe
that, in a situation where the crust of the earth was con-
tinuously in motion over an extended period, a build-up
of heat in the crust might cause considerable melting in its
lower parts where the temperature was already very close to
the melting points of the rocks. This increase of heat would
link itself quite naturally, therefore, to an increase in the
number and intensity of volcanic eruptions, and to lava flows
of all kinds. By means of these eruptions and flows some of
the heat would be dissipated into the air; much of it, how-
ever, imprisoned in the lower part of the crust, would simply
increase the volume of the molten magmas.
While the increase of heat in the crust would naturally
favor larger lava flows, another factor would create the pos-
sibility of massive flows, or lava floods. A massive displace-
ment of the crust, because of the oblateness of the earth,
must produce temporary distortions of its shape, and of the
gravitational balance of the crust. The force of gravity sub-
sequently must gradually force the crust to resume its normal
position. This, of course, involves great pressure upon the
crust, and upon the molten or semimolten liquid material
under or within the crust. Pressures of this kind might oc-
casionally lead to the eruption of plateau basalts. The prob-
able magnitude of the distortions of the crust resulting from
displacement will be considered in detail later on. It must
not be supposed, however, that every displacement of the
crust must inevitably produce lava floods. The latter would
perhaps be the result of an unusual combination of pressures
and fractures. The same combination of forces which might,
in one situation, produce volcanic mountains and island arcs
i2o EARTH'S SHIFTING CRUST
might, under other circumstances, produce a doming up of
the crust in a local area or a lava flood.
p. Changing Sea Levels
An important problem closely related to that of mountain
building is that of the cause of very numerous, and in some
cases radical, changes in the elevations of land areas rela-
tively to the sea level. Umbgrove finds that mountain folding
has been related, in geological time, with uplift of land areas,
or with withdrawal or regression of the sea (430:93). How-
ever, it is clear that the uplifts were not confined merely to
the folded areas, that is, to the mountains themselves, but
affected large regions. Such uplifts, where whole sections of
the earth's crust were elevated without being folded, are re-
ferred to as epeirogenic uplifts, to distinguish them from the
uplifts of the folded mountain belts which may have re-
sulted from the folding itself, and which are referred to as
orogenic uplifts. As to the extent of the resulting changes in
sea level, Umbgrove says:
. . . The most important question concerns the depth to which
the sea-level was depressed in distinct periods of intense regression,
in other words, the extent of the change to which the distance be-
tween the surface of the continents and the ocean floors was subjected
during the pulsating rhythm of subcrustal processes. Joly was the
only one who approached this question from the geophysical side,
and he arrived at an order of 1000 meters. . . . (430:95).
It becomes necessary, therefore, to find a connection be-
tween the cause of the folding of the crust and the cause of
general, or epeirogenic, changes of elevation of continents
and sea floors. Fortunately, this problem is not really so diffi-
cult as it may seem at first glance. That it can be solved in
terms of the assumption of displacements of the earth's crust
is, I think, clear from the following considerations.
Gutenberg has pointed out that if a sector of the crust, in
gravitational equilibrium at the equator, is displaced pole-
THE MOUNTAINS 121
ward by a shift of the whole crust, it will be moved to a
latitude where gravity is greater, because gravity increases
slightly toward the poles. Its weight will be thereby in-
creased, and to remain in gravitational equilibrium it must
seek a lower level: it must subside. The water level in the
higher latitude adjusts easily, of course. Gutenberg points out,
however, that if the movement of the crust occurs at a rate
greater than the rate at which the sector may sink, by dis-
placing viscous material from below itself, the result will be
that the sector will stand (for a time) higher relatively to sea
level than it did before. I give Gutenberg's own words:
Movements of the earth's crust relative to its axis must be accom-
panied by vertical displacements. A block with a thickness of 50
kilometers in equilibrium near the equator should have a thickness
of 49.8 near the poles to be bounded by the same equipotential sur-
faces there. If it moves toward a pole, it must sink deeper to keep in
equilibrium. If the process is too fast for maintenance of isostatic
equilibrium, positive gravity anomalies and regressions are to be ex-
pected. Thus regression may be an indication that an area was moving
toward a pole, and transgressions that it was moving toward the
equator (194:204-05).
According to Gutenberg, an area moved about 6,000 miles
from the equator to a pole would stand about 1,200 or 1,400
feet higher above sea level, if the speed of the displacement
was too rapid for maintenance of gravitational equilibrium.
The speed of displacement that is suggested by the evidence
to be presented later is such as to eliminate entirely the
possibility that the crustal sector could sink and remain in
gravitational equilibrium. Consequently, by our theory, a
poleward movement of any sector of the crust will result in
uplift, and in regression of the sea. In addition, it appears
to me that since any sector displaced poleward would also
be compressed laterally, this would offer another obstacle to
its subsidence. It would have to overcome the lateral pres-
sures, as well as displace underlying material.
The amount of the uplift of an area displaced poleward
would depend, of course, on the amount of the displacement.
As will be made clear later, much geological evidence ap-
122 EARTH'S SHIFTING CRUST
pears to suggest that displacements may have amounted, on
the average, to no more than a third of the distance from a
pole to the equator. If this is true, then the resulting uplift
to be expected should be of the order of about one third of
the uplift he suggested, or from 400 to 500 feet. We shall see,
later, how well this agrees with the evidence.
There is another factor that would operate in the same
direction as the effect mentioned by Gutenberg, to alter the
elevation of land areas and sea bottoms. Unlike the gravita-
tional effect, however, this second factor would tend to a
permanent change in sea levels, and might therefore, cumu-
latively, result in important changes in the distribution of
land and sea. It is a question of the permanent consequences
of the stretching or compression of the crust. As we have
seen, an area displaced poleward must undergo compression
because of the shortened radius and circumference of the
earth in the higher latitudes. This compression must result
in the folding of rock strata, which will be likely to occur
mainly in areas where the crust has already been weakened
by the formation of geosynclines. The effect of the folding
will be to pile up the sedimentary rocks that have been
formed from sediments deposited in the geosynclines, caus-
ing them to form thicker layers. These thicker layers of
lighter rock will tend, even after gravitational adjustments
have taken place, to stand higher above sea level. The effect
of one displacement in this respect would be slight, but the
accumulation of the effects of many displacements through
millions of years could lead to extremely important changes
in the distribution of land and sea areas. Numerous displace-
ments of the earth's crust could, in fact, constitute an essen-
tial, and perhaps even the basic, mechanism for the growth
of continents.
Equally important for the general question of sea levels
are the effects to be expected from a displacement of a sector
of the crust toward the equator. Here the crust will be sub-
jected to tension, or stretching. We have already noted that
in this process innumerable fractures will be created in the
THE MOUNTAINS 12$
crust, and these will tend to be filled up with magma from
below. Since this magma, invading the crust, will average
higher specific density than the rocks of the crust, it may in-
crease the general weight of the crust, and thus depress it,
causing a deepening of the sea. This would not occur if the
separated blocks simply sank in the underlying magma until
they displaced their own weight, in the manner suggested by
Campbell. In that case, the crust would weigh no more than
before. It seems, however, that volcanic activity is accom-
plished by very complex chemical processes, and by the ab-
sorption of vast quantities of lighter rock and its transforma-
tion chemically into heavier rocks, to the accompaniment
of much throwing off of gases into the atmosphere. It is also
true, as we have noted, that massive lava flows may occur on
the sea bottoms (or even, perhaps, within the crust, at points
below the sea bottoms) as a result of displacement of the
crust. These could have the effect of weighting the crust.
Moreover, an equatorward displacement of an area must
result in a gravitational effect opposite to that of the pole-
ward displacement mentioned by Gutenberg. In this case,
the crust must rise to achieve gravitational balance. In so
doing it may have to draw into itself a considerable amount
of the heavier rock underlying the crust. This obviously
would tend to weight the crust.
The foregoing factors, added together, may account for
the observed deepening of the oceans, and the increase of
their total surface area, from the poles to the equator. A
careful survey indicates that this deepening is on the order
of one kilometer or, perhaps, 4,000 feet (233).
There is still another factor that may affect sea levels,
but in an unpredictable way. It seems clear, for several rea-
sons, that a displacement of the earth's whole crust must
result in considerable readjustments and redistribution of
materials of different densities on the underside of the crust.
While these can hardly be predicted, they must affect the
elevation of points at the earth's surface.
Geologists believe that the underside of the crust has un-
124 EARTH'S SHIFTING CRUST
evennesses, corresponding to those at the surface, and that
the crust varies considerably in thickness from place to place.
They think, for example, that the crust is thicker under the
continental surfaces, and thinner under the oceans, and that
it is thickest of all under mountain ranges and high plateaus.
Continents and mountain ranges not only stick up higher
but they also stick down deeper. That is because they are
composed, as an average, of lighter rock. The analogy is to
an iceberg. An iceberg floats with one tenth of its mass above
sea level, and nine tenths of it submerged. It is lighter than
water per unit volume, and floats in the water displacing its
own weight, and leaving its own excess volume above the
surface. Continents and mountain chains, composed on
the average of lighter rock, stand in the same sort of hydro-
static, gravitational balance, and their downward projections
are thought to be much greater than their upward, visible
projections. The downward projections of mountain chains
are called "mountain roots."
The underside of the crust, then, has a sort of negative
geography. The features of the upper surface are repeated in
reverse on the undersurface, although, naturally, the details
are missing. The effects are rather smoothed out. We should
expect that the Rocky Mountains would make a sizable
bump on the underside of the crust, but we couldn't expect
to find any small, sharp bump just under Pikes Peak. The
tensile strength of the crust, though limited, is sufficient to
smooth out the minor features.
As we attempt to envisage the situation at the bottom of
the crust, we must remember that the rocks are subjected to
increasing pressure with depth, and probably to increasing
heat, and as a consequence they must tend to lose their rigid-
ity and strength. We don't just come suddenly to the bound-
ary of the crust at a given depth. On the contrary, the crust
just fades away. The rocks of the lowest part of the crust
must be very weak indeed, so that a very slight lateral pres-
sure may suffice to displace them.
THE MOUNTAINS 125
It follows that when lateral pressures develop during a
displacement of the crust, as the downward projections of
continents and mountains are brought to bear against the up-
ward extension of the viscous layer below the ocean base-
ments, large blobs of this soft rock of lesser density will be
detached from the undersides of the continents, or mountain
ranges, and will get shifted to other places. If, as a result of
this shifting around, the average densities of vertical columns
extending from the bottom to the top of the crust get
changed, then there will eventually be corresponding changes
of elevation at the surface. Some areas might, as a result, tend
to rise, and others to sink. This could account, naturally, for
changes of sea level, and for many topographical features
such as basins and plateaus.
To sum up the question of sea levels, it appears that the
assumption of displacements of the crust (especially if they
are considered to have been numerous) may help to explain
them. It seems able to explain why glaciated areas (which
we consider to have been areas displaced poleward) appear
to have stood higher relatively to sea level, and why periods
of warm climate in particular regions appear to have been
associated with reduced elevation of the land, and transgres-
sions of the sea. The theory seems to satisfy Umbgrove's
conclusion that sea-level changes have resulted from some
"world-embracing cause" (430:93). It accounts, too, for
Bucher's suggestion that regressions of the sea have resulted
from subcrustal expansion, and transgressions from sub-
crustal contraction, for this, obviously, is only another way
of looking at a displacement of the crust (58:479). (If an area
is displaced poleward, the effect of subcrustal contraction is
created; if it is displaced equatorward, the effect of subcrustal
expansion occurs.) At the same time it provides an explana-
tion for the rhythmic changes of sea levels through geological
history that so mystified Grabau:
This rhythmic succession and essential simultaneousness of the
transgressions as well as the regressions in all the continents, indicates
126 EARTH'S SHIFTING CRUST
a periodic rise and fall of the sea-level, a slow pulsatory movement,
due apparently to alternate swelling and contraction of the sea-
bottom (183).
jo. Some Light from Mars
Some very significant facts emerge from recent studies of
other members of the solar system, especially from the work
of Dr. Harold Urey, The Planets: Their Origin and Develop-
ment (438). This is the work in which the theory of accretion
of planets is developed, in contradiction to the older theory
of the cooling globe. Dr. Urey also discusses the present state of
knowledge regarding the structure of the moon and Mars.
It appears that there are mountains on the moon, but in
Dr. Urey's opinion these have been created by collisions with
minor celestial bodies. Where the colliding body hit the
moon more or less head on, craters (the largest more than 100
miles across) were formed. Planetesimals that merely grazed
the moon's surface left long ridges and valleys. Where the
heat created by the impacts caused extensive rock melting,
vast lava floods apparently took place, which cooled off, in
tens or hundreds of thousands of years. The absence of air
and water has resulted in an absence of erosion on the moon's
surface, so that the features created by the collisions have
not been obliterated except in cases where the lava flows have
swamped them.
In the case of Mars, the story is different. Urey assumes
that Mars was once like the moon, both in size and in surface
features. The removal of these features, which no longer
exist, he thinks must have been due to the work of atmos-
phere and water. He gives reasons for believing that Mars
did have more water at one time, but that it escaped from
the planet by a process that is also going on, more slowly, on
earth. He states:
. . . The surface appears to be smooth, a condition most easily
explained as due to the action of water during its early history and
no mountain building since then (438:65).
THE MOUNTAINS 127
In another place he says:
. . . Mars appears to have no high mountains, and it is difficult to
understand this unless it had some initial water. (In order for it to
remain without mountains no folded mountains must have been
formed subsequently; but this is another subject.) The formation of
Mars and its surface followed a course similar to that of the earth
So we see that Mars and the earth appear to have followed
similar courses of development. They are similar in chemical
composition and in structure, and have similar atmospheres.
There are, apparently, only two important points of differ-
ence, other than size. Mars, unlike the earth, has very little
water, so that its polar icecaps are thought to be no deeper
than hoarfrost, and disappear entirely in summer; and Mars,
unlike the earth, has no folded mountains.
A thought-provoking fact: on Mars, no great icecaps-— and
no folded mountains, no volcanic phenomena, no fault
mountains! Surely this is no coincidence. Surely, it is sugges-
tive of the fact that these features on earth have been the
consequence of displacements of the crust, and that these dis-
placements have been owing to the agency of great polar ice-
caps. It might seem, at first glance, that the absence of folded
mountains on Mars might be explained by the absence of
deep accumulations of sediments produced by the weather-
ing of rocks under the action of water, and the accumulation
of these sediments in geosynclines with subsequent folding,
but we have seen that geologists do not claim to explain the
original creation of the geosynclines, nor to identify the source
of the compressive stress that brings about mountain folding.
ii. Undisturbed Sections of the Crust
It has been objected that over extensive areas there are rock
formations that appear to have been little disturbed over
very great periods of time. If the crust has been displaced
128 EARTH'S SHIFTING CRUST
as often as is required by this theory, why would not the crust
be universally folded to a far greater extent than it is?
I think this objection has been partly answered where I
pointed out that in a single displacement of the crust the
folding would be comparatively slight, and that it would be
confined to a small part of the earth's entire surface. I have
suggested that it would be greatest along the meridian of the
crust's maximum displacement, but that at some point be-
tween this meridian and the two areas suffering no displace-
ment, the compressions would tend to fall below the elastic
limit of the crustal rocks, so that the crust would simply bend
elastically, and then return to its original, apparently undis-
turbed position, in some subsequent movement. It may be
added that most of the changes of elevation resulting from a
displacement of the crust would tend to be epeirogenic— that
is, they would be broad uplifts or subsidences of large regions
resulting from the tilting of great segments of the crust,
rather than merely local deformations of the rock structures.
Another point that may be urged in answer to this objec-
tion is that, apparently, over considerable periods the poles
have tended to be situated again and again in approximately
the same areas, possibly owing to the configuration of the
continents. This would result in leaving some areas far re-
moved for long periods from the meridian of maximum dis-
placement of the crust.
12. The Chronology of Mountain Building
Another objection that may be raised to this theory of
mountain building is that there are supposed to have been
only a few great mountain-making epochs in the world's his-
tory of two or more billion years, and that these epochs have
been separated by very long periods when mountains were
eroded away, and no new ones made. I shall indicate two
reasons for holding that this concept is an illusion.
The first reason is that the record of the rocks is incom-
THE MOUNTAINS 12Q
plete. It has been estimated that if all the sedimentary beds
of all geological periods were added together (that is, the en-
tire amount of sediment that has been weathered out of the
mountains and continents and accumulated to make sedi-
mentary rocks since the beginning of geological time), the
total thickness of sediment would be about eighty miles. At
the present time, however, the average thickness of the sedi-
mentary rocks of the upper part of the earth's crust is esti-
mated to be no more than a mile and a half (333). What has
happened to all the missing sediment? The answer is that it
has been used over again. At the present time, all over the
earth, the forces of the weather and the sea are busy wearing
away or grinding up rock, and most of the rock they are
destroying is sedimentary rock. Thus more than 95 per cent
of all the sedimentary rocks formed since the beginning of
the planet has been destroyed. As a result of this, geologists
have been forced to piece together this geological record
from widely separated beds. They find a part of the Silurian
sediment in the United States, and another part in Africa,
and so on.
The enormous difficulty of piecing together the geological
record from these discontinuous and scattered beds is ren-
dered even greater by the fact that vast areas of what were
once lands are now under the shallow epicontinental seas,
and even under the deep sea (as we shall see in the next
chapter). Let us remember, too, that even among the still-
existing beds now to be found on the lands, only a tiny
percentage are at or near the surface and thus available for
study. And of these a large proportion are in such remote
and geologically unexplored areas as Mexico, the Amazon,
and Central Asia. And still, despite these enormous handi-
caps, new periods of mountain formation are constantly be-
ing discovered. Umbgrove remarks that a long list of them
has been "gradually disclosed to us" (430:27). It seems to me
that there is unjustifiable complacency in the assumption
that the list of mountain-forming epochs is now complete.
130 EARTH'S SHIFTING CRUST
How can we reach a reasonable guess as to the number that
remain undiscovered?
The second reason for holding that the idea of rare moun-
tain-building periods is quite illusory is perhaps even more
persuasive. It seems that a remarkable error has vitiated the
interpretation of the evidence regarding these alleged pe-
riods. The error has been exposed by the development of
nuclear methods of dating recent geological events, already
referred to, and to be discussed more fully later. These have
revealed an unexpectedly rapid rate of geological change.
The error, I think, consists in interpreting the geological
evidence on the assumption that conditions as revealed in a
particular deposit in one area necessarily determine world-
wide conditions. Thus, evidence of an ice age in a particular
deposit in one place has been interpreted as meaning a period
of lowered temperature for the whole world at that time. In
the same way, mountain-building revolutions were assumed
to affect all parts of the world at once. The idea that moun-
tain building might go on on one continent while another
went scot-free was not entertained.
The contemporaneousness of these events in different parts
of the world rested, as we shall see, upon a very vague idea of
geological time. The techniques for dating the older geo-
logical formations never did, and do not now, allow reliable
conclusions regarding the contemporaneousness of moun-
tain building on different continents any more than they
permit such conclusions regarding climatic changes. Margins
of error amounting to millions of years must always be al-
lowed. Triassic folding in India need not be contemporary
with Triassic folding in North America, because the Triassic
Period is estimated to have lasted about 35,000,000 years!
Calculations of the rates at which the weather wears away
mountains have shown that mountain ranges may be worn
away in much less time than that.
Thus, we cannot place reliance on the accepted notions of
the occurrence of mountain-building revolutions in time and
space, but must hold that the process was, in all probability,
THE MOUNTAINS 1J1
much more continuous than has been supposed, but confined
to smaller parts of the earth's surface at any one time. Further
support for this view is provided by the geologist Stokes, who
remarks, in connection with the history of the Rocky Moun-
tains:
Although the Rocky Mountain or Laramide Revolution is popu-
larly supposed to have occurred at the transition from the Cretaceous
to the Tertiary, it has become increasingly evident that mountain
building was continuous from place to place from the late Jurassic or
early Cretaceous and that deformation continued through the early
Tertiary and Quaternary (405:819).
In other words, mountain building went on continuously in
North America from the Jurassic Period, about 100,000,000
years ago, into the Pleistocene Epoch, which is considered to
have come to an end 10,000 years ago! This is excellent evi-
dence in support of the conclusion that, in all probability,
none of the alleged mountain-building revolutions occurred
in widely separated periods, with long, quiet periods in be-
tween.
Krumbein and Sloss point out that this view is, in fact, be-
coming widely accepted by geologists. They remark that
"Gilluly . . . recently examined the evidence for and against
periodic diastrophic disturbances, and he showed that such
disturbances are much more nearly continuous through time
than is generally supposed," and they conclude:
Added complexity arises as additional stratigraphic studies afford
data which imply that tectonic activity is continuous through time.
The classical concept that a geological period represents a long in-
terval of quiescence closed by diastrophic disturbances is not fully
supported by these newer data (258:343).
V : CONTINENTS AND OCEAN BASINS
i. The Central Problem
None of the mysteries of the earth is more baffling than the
question of the origin and history of the continents and ocean
basins. One of the most useful applications of the theory of
crust displacements will be its application here.
As with the problems already considered, there are many
theories that are in violent conflict. The conflict is broad and
deep, and since it involves two or three branches of science,
which have adopted antagonistic points of view, it may even
be called a civil war in science. It is fought over one issue:
whether the present continents and deep ocean basins have
been permanent features of the earth's crust since the forma-
tion of the planet, or whether they have not.
It would take too long to review the history of this war, for
it extends far back into the nineteenth century. Instead, it
will suffice to outline the principal positions adopted by the
antagonists. Before we do this, however, it is essential to
emphasize that most contemporary geologists, knowing the
mystery surrounding these principal features of the earth's
surface, have refrained from making very positive statements.
Professor Daly, for example, after admitting that the forma-
tion of continents could not be accounted for under the
theory of the solidification of the crust from an originally
molten state, remarked that
We are now face to face with a principal mystery of nature. Ac-
tually, the earth's substance is differentiated into the form of conti-
nent overlooking deep ocean basin. That obvious, infinitely important
fact, dry land on a continental scale, has to find its place in any theory
of the earth. The problem is as difficult as it is fundamental. . . .
Daly goes on to say that all he is able to offer on the subject
is a guess, but that any reasonable guess is better than simply
CONTINENTS AND OCEAN BASINS 1J3
avoiding the issue, which, he observes, is the course too often
taken.
Daly's own guess will not do for us, because it is based both
on the theory of an originally molten globe and on the theory
of drifting continents. He suggests that when the earth was
entirely molten, the lighter rock, which now forms the gra-
nitic foundations of the continents, was floating on top of
the heavier rock, of basaltic composition, and crystallized
first, making a thin layer over the planet's whole surface.
Then, for some reason (not entirely clear) all this lighter
rock slid toward one hemisphere and piled up, making a
supercontinent. Later this supercontinent broke up and
drifted apart, as suggested by Wegener.
Jeffreys also refers to the difference between the aver-
age chemical composition of the continents and that of the
ocean floors. There is a difference in the densities of the two
kinds of rock, and this is the reason why the continents stand
high and the ocean beds are low. But what brought about
this difference of composition is itself unexplained. It is, says
Jeffreys,
. . . closely connected with the great problem of the origin of the
division of the earth's surface into continents and ocean basins, which
has not yet received any convincing explanation (239:159).
Professor Umbgrove also has admitted that the field is
wide open to any reasonable speculation. He feels that he
is confined to mere guessing, but justifies what he writes
thus:
. . . But why should we not enter [this field] if everyone who wants
to join us in our geopoetic expedition into the unknown realm of the
earth's early infancy is warned at the beginning that probably not a
single step can be placed on solid ground? (430:241).
In view of this state of affairs, I shall not apologize if, at
times, in the course of this and the following chapter, I shall
seem to the reader to be venturing beyond the point where
speculation can be immediately checked by the facts. To a
certain extent, my suggestions will be simply logical deduc-
EARTH'S SHIFTING CRUST
tions from the general theory of crust displacements, and
may be incapable, at least at this stage, of direct proof.
2. The Views of the Geophysicists
In this civil war between the sciences, the first group I shall
call upon to present their side of the case are the geophysi-
cists. Now the geophysicists, by and large, have very definite
views about the continents, even though they cannot explain
their origin. Their consensus is that the continents have been
permanent features of the earth's crust from the "beginning,"
and this involves an equal permanence for the ocean basins.
Changes of sea level there have been: so much cannot be de-
nied; but according to the geophysicists these can have been
only relatively important. At times the continental shelves
(the narrow strips along the coasts where the water is only a
few hundred feet deep) have been laid bare, and at other
times the oceans have invaded the low parts of the conti-
nents, but such changes (while unexplained) have been
slight; they have not affected the main masses of the conti-
nents. The continents, then, are original features dating, in
their present positions, from the unknown beginnings of the
planet.
Of course, geophysicists would never make such broad
statements as these, unless they had what seemed to them
sufficient evidence. Their argument is easily stated. They
point to the differences in composition. The continental rock
is less dense, on the average, than the rock under the oceans.
The force of gravitation brings all sectors of the earth's crust
into rough balance, and this means that the lighter parts will
stick up higher, like pieces of wood or ice floating on water.
The continental sectors of the crust are considered to be both
lighter and thicker than the oceanic sectors. The greater
thickness makes up for the less density, so that things bal-
ance off.
This principle of the gravitational balance of the crust is
CONTINENTS AND OCEAN BASINS 135
referred to as the principle of "isostasy." We shall see, later,
that there are some serious difficulties with the general theory
of isostasy, as a consequence of which it cannot be regarded
as definitely established. Still, on the whole, there is much to
be said for it. And so the geophysicists ask how can anything
alter the major concentrations of lighter or heavier rock,
which, according to the theory of isostasy, must determine
the locations of continents and ocean basins? A continent
could not be destroyed without getting rid of a large amount
of lighter granitic and sedimentary rock, and a new conti-
nent could not be raised up without producing a vast amount
of new rock of that kind. Since these things are impossible,
changing continents around is impossible, and the less said
about it the better.
3. The Views of the Biologists
While the geophysicists were developing these ideas, based
upon laboratory experiments and principles of physics, the
biologists and paleontologists were busily engaged with an
entirely different question, which led them to diametrically
opposite conclusions. They were classifying and comparing
plants and animals from all parts of the world, those living
today and those that lived in ages past. They were soon con-
fronted by the fact that in many cases the same species of
plants and animals could be found on lands separated by
whole oceans. How was this to be explained? It could not
be maintained that all these forms of life— snails, grasshop-
pers, ferns, fresh-water fish, and elephants— had all built
rafts, like Kon~tiki, in which to cross the Pacific. Nor was it
possible to explain the distribution of all sorts of species by
means of ocean currents, migratory birds, or winds. Behring
Strait would not do either, because the plants and animals
of the warm climates could hardly be tempted to chance the
rigors of the Arctic merely to reach America or to escape
from it.
136 EARTH'S SHIFTING CRUST
As we have seen, when the paleontologists studied the life
of the remote past they found the same thing. The distribu-
tions of the fossil plants and animals did not seem to pay
any attention to the present shapes or positions of the conti-
nents. Therefore, not knowing what the geophysicists were
up to— or not caring— the biologists and paleontologists de-
cided between themselves that they were in need of some new
continents, or rather, in need of some old, now nonexistent
continents, or at least a large number of former land con-
nections across the present oceans. And so they went right
ahead, and invented them.
Wegener, of course, managed to explain a mass of evidence
by moving the continents (450:73-89). Since the refutation
of his theory, the same evidence needs a new explanation.
Dodson gave the evidence for a North Pacific land bridge
(not Behring Strait) based on the distributions of 156 genera
of plants (115:373). Gregory also produced evidence for a
Pacific land bridge (191). DeRance and Feilden presented the
evidence for a land connection between North America and
Europe in the early Carboniferous (319:!!, 331-32). Cole-
man, basing himself no doubt on paleontological evidence,
remarked that "India has many times been connected with
Africa" (87:262).
Dodson reconstructed the history of the Isthmus of Pan-
ama, as indicated by the distributions of fossil plants and
animals. According to him, North and South America were
connected in the Cretaceous and in the early Paleocene, but
later in the Paleocene, Panama was completely submerged.
During the following Eocene and Oligocene there were islands
but no continuous land in the area. The islands were com-
pletely submerged late in the Oligocene. Land connection
between the continents was re-established in the Pliocene,
that is, very lately (115:375-76). It must be emphasized that
the explanation for all these land changes is missing. There
is no basis in the geological evidence for the assumption that
the isthmus was never more than just barely submerged.
There is no reason to exclude the possibility that it was rather
CONTINENTS AND OCEAN BASINS 137
deeply submerged at times. Later I shall show that the prob-
lem cannot be solved by any theory that the melting of ice-
caps in "interglacial periods" periodically raised the water
level.
One writer, who is considered a very special authority on
the climates of the past, Dr. C. E. P. Brooks, gave a list of
continents that must have existed about 300,000,000 years
ago, if the distribution of plants and animals at that time is
to be explained. He even names them (52:247-51):
a. Nearctis, a "primitive North American continent/'
b. North Atlantis, including Greenland and western Eu-
rope.
c. Angaraland, occupying part of the present Siberia.
d. Gondwanaland, a huge continent extending from South
America to India via South Africa.
He states, further, that the evidence shows that Nearctis
and North Atlantis were connected by a land bridge at about
Lat. 50° N., and that the first three continents were separated
from Gondwanaland by a great ocean, the Tethys Sea, which
extended from New Guinea to Central America. Another
authority, Beno Gutenberg, writes:
. . . Nearly all specialists on such problems conclude that during
certain p re-Tertiary periods land connections existed across sections
of the present Atlantic and Indian Oceans. . . . During certain geo-
logical periods land life was able to roam from land to land; on the
other hand, such former connections of continental areas prevented
sea life from moving from one part of the Atlantic to another (194:
208-09).
Gutenberg thus bears witness to the fact that the sea lif<
as well as the land life of the past supports the idea of im
portant changes in the positions of land masses.
We can see that the suggestions advanced are of two kinds:
sunken continents, and changing land bridges between conti-
nents. Land bridges, of course, are more easily explained
than sunken continents. However, we shall see that, for a
number of reasons, they will not suffice of themselves. There
138 * EARTH'S SHIFTING CRUST
is evidence that points insistently to the former existence o£
whole continents in what are now oceanic areas. Only re-
cently, for example, Dr. Albert C. Smith, of the Smithsonian
Institution, concluded, from a massive study of the plants of
the islands of the Southwestern Pacific, that the islands must
be merely the remnants of an ancient Melanesian continent
that broke up about 10,000,000 or 20,000,000 years ago (397).
We shall see that there is plenty of evidence, besides the evi-
dence of fossils, to support his conclusion.
From what has been said about mountain formation, I
think it is clear that the matter of the appearance and disap-
pearance of land bridges is accounted for at the same time that
the mountain ranges are accounted for. A displacement of
the crust will lead to the uplift of long, narrow, folded tracts
on the sea bottom as well as on land. One of these, coming
into existence on the bottom of a shallow sea between two
major land masses, could connect such land masses and con-
stitute a land bridge. Its subsidence in a later movement of
the crust could separate the land masses, and the subsidence
could be partial, leaving islands, or total.
It is interesting to see that Umbgrove found himself com-
pelled, because of a mass of geological evidence, to support
a theory of rapidly appearing and disappearing land bridges,
which was advanced by Willis and Nolke, though he ad-
mitted that * 'Their origin and submersion will probably re-
main a mystery for some time to come. . . ." (430:238).
Land bridges have been very convenient for many sci-
entists seeking to avoid the horrid alternative of former
continents. According to the picture drawn by some writers,
these bridges were long snakelike arms, wriggling out this
way and that, which just happened to make the right connec-
tions between the right continents at the right times for the
convenience of the right plants and animals. Often when the
threat of a former continent loomed so imminently that its
avoidance seemed hopeless, a land bridge would save the day.
Most paleontologists were satisfied with land bridges, and did
not insist on sunken continents, but some could not help
CONTINENTS AND OCEAN BASINS 13
feeling that there was something artificial about the idea
they therefore continued to speculate about former conti
nents.
Should you ask, How did all this activity on the part o
the biologists and paleontologists strike the geophysicists
I can answer that it did not strike them at all. This can b<
explained partly by the fact that geophysicists generally d<
not read books on paleontology, and vice versa. So far as tin
geophysicists were concerned, the speculations of the paleon
tologists could be discounted as the insubstantial imagining
of persons unacquainted with geophysics. To study the bio
logical literature allegedly supporting these speculations was
of course, not the function of geophysicists. It was outsid<
their field, and, moreover, beyond their competence. Th<
connection between these sciences was a distant one. The re
lations between them were cool, to say the least.
4. Geologists Allied with Biologists
It would have been a sad thing for the biologists and paleon
tologists had they not been able to find allies in the sever<
struggle in which they were engaged (without, for the mos
part, being aware of it). But find allies they did. For it soor
developed that the geologists would not be content with th<
limitations on continental change imposed by the geophysi
cists. They could not be satisfied with land bridges. Fron
purely geological studies of the stratified rocks of many land
throughout the world came quantities of evidence insistently
suggesting that the continents and ocean basins could no
have had the permanence demanded by existing concepts ir
geophysics.
To begin with, there is an extraordinary contradiction ir
the very fact that, while continents are supposed to have beer
permanent, nearly all the sedimentary beds that compos<
them were laid down under the sea. There is no denying thi
140 EARTH'S SHIFTING CRUST
fact. According to Schuchert, North America has been sub-
merged no less than seventeen times (gGgaiGoi). According
to Humphreys, the sea has covered as much as 4,000,000
square miles of North America at one time (231:613).
Termier argued that the sedimentary beds composing the
mountain ranges extending eastward from the Alps to Cen-
tral Asia, which were laid down under the sea, would have
required that the ancient Tethys Sea, in which they were laid
down, should have been about 6,000 kilometers (or perhaps
4,000 miles) across (419:221-22).
Geophysicists tend to argue that such seas, which clearly
did exist, were merely shallow affairs, invasions of the conti-
nents by the ocean owing to some unknown cause. The posi-
tive evidence for this, based on the apparent absence from
the sedimentary rocks of sediments formed in the very deep
sea, has a fallacy in it, as will be made plain later. The posi-
tive evidence against the assumption that all these seas were
shallow seas is, on the other hand, enormously strong. Umb-
grove, for example, remarks:
. . . Not only have parts of the continents foundered below sea-
level since pre-Cambrian times but they have even done so until quite
recently, and their subsidence occasionally attained great depths! The
present continents are but fragments of one-time larger blocks. . . .
(430- 3°)-
A particularly important example of such foundering
seems to have occurred in the North Atlantic, off the north-
eastern coast of the United States. It has been found that the
sediments that compose the northeastern states were derived
in ages past from a land mass to the eastward in the present
North Atlantic. This could have been Brooks's continent of
North Atlantis.
Some geologists, cowed by the geophysicists, have at-
tempted to argue that these sediments might have been de-
rived from a land mass situated on the present continental
shelf, but the argument fails from every point of view. Brew-
ster, for example, comments:
CONTINENTS AND OCEAN BASINS 141
It must have been a large continent, for the sand and gravel and
mud which the rivers washed out to sea and the waves ground up on
the shore have built up most of half a dozen big states, while in some
places the deposits are a mile thick (45:134-35).
Umbgrove says that while it is impossible to estimate the
size of the land mass (called "Appalachia" by the geologists),
it was clearly large, to judge from the fact that it has been
possible to trace out in the sedimentary beds of the Appa-
lachian Mountains the outline of an enormous delta formed
by a giant river flowing out of the land mass to the east
(430:35-38).
Now the continental shelf of North America ends abruptly
a very short distance from the coast. It is an extremely narrow
strip between the coast and the so-called "continental slope,"
where the rock formations dip down suddenly and steeply
into the deep sea. Its average width is only 42 miles, and its
maximum width does not exceed 100 miles (46). If the sedi-
ments had been derived from a land mass on this continental
shelf, this very narrow land mass would have had to carry
huge and repeatedly uplifted mountain ranges. Further-
more, since drainage would naturally have carried sediments
down both slopes of these mountain ranges, a large propor-
tion of the material would have been carried eastward and
deposited in what is now the deep ocean; but there is no evi-
dence of this.
The suggestion that the enormous volume of sediments
forming the northeastern states of the United States came
from the continental shelf must be considered improbable. On
the other hand, it is plain that the former continent in the
North Atlantic could not have been eroded away by rivers
any farther down than approximately sea level. Erosion did
not dispose of the continent, nor create the deep-sea basin.
After erosion had finished its work, the continent itself sank
to a great depth. Umbgrove has cited recent oceanographic
research by Professor Ewing of Columbia, showing that this
ancient land mass of Appalachia now lies subsided about two
miles below the continental shelf (430:35-38).
142 EARTH'S SHIFTING CRUST
This extraordinary case is by no means unique, for Umb-
grove has pointed out that the sediments composing much
of Spitsbergen and Scotland come from the ocean west of
them, while those composing the west coast of Africa come
from a former land mass in the present South Atlantic. Most
interesting of all, he indicates that the deepest of the world's
deep-sea troughs (east of the Philippines), about seven miles
deep, gives evidence that it was once part of a very large con-
tinent (430:38).
The evidence produced by Coleman, showing that a conti-
nental ice sheet once invaded Africa from the sea, and that
the Indian ice sheet must have extended on land far to the
south of the present tip of India, is to the same effect. It
serves to answer conclusively the argument about continental
shelves. You can put just so much on a shelf.
According to Umbgrove, there is ample evidence of re-
peated upward and downward oscillations of the floor of the
entire Pacific (430:236). In a kind of rhythm, the great ocean
has become alternately shallower and deeper. In the absence
of any explanation of this phenomenon, Umbgrove becomes
geopoetic. There seems to him to be something almost mysti-
cal in this slow pulsation of the living planet. He finds that
the unexplained upward and downward movements are not
limited to sea areas:
... It should be noted that blocks that were first submerged, then
elevated, and then once more submerged and elevated, are also met
with on the continents. The sub-Oceanic features and the similar
continental characteristics cannot be explained at present, for our
knowledge of pre-Cambrian history and terrestrial dynamics is not
yet extensive enough. . . . (430:241).
Comparatively radical vertical changes in the positions of
land masses are evidenced by a considerable number of an-
cient beaches (some of them, however, not very old) which
are now found at great elevations above sea level, and some-
times far inland from the present coasts. Thus the geologist
P. Negris claimed to have found evidences of beaches on
three mountains of Greece: Mt. Hymettus, Mt. Parnassus,
CONTINENTS AND OCEAN BASINS 143
and Mt. Geraneia, at, respectively, 1,400 feet, 1,500 feet,
and 1,700 feet above sea level. He found a beach on Mt.
Delos at 500 feet (3243:616-17). William H. Hobbs cited
a particularly interesting case of a beach of recent date now
1,500 feet above sea level, in California:
Upon the coast of Southern California may be found all the fea-
tures of wave-cut shores now in perfect preservation, and in some
cases as much as fifteen hundred feet above the level of the sea.
These features are monuments to the grandest of earthquake dis-
turbances which in recent times have visited the region (216:249).
It would be possible to multiply endlessly the evidence of the
raised beaches, which are found in every part of the world.
Many of them may imply changes in the elevations of the sea
bottoms, such as are suggested by Umbgrove.
One of the most remarkable features of the earth's surface
is the Great Rift Valley of Africa. The late Dr. Hans Cloos
pointed out that the high escarpment along one side of this
valley was once, quite evidently, the very edge of the African
continent: not just the beginning of the continental shelf,
but the very edge of the continental mass. In some vast move-
ment that side of the continent was tremendously uplifted,
and the sea bottom was uplifted with it as much as a mile,
and became dry land. This is so interesting a matter, and of
such special importance for our theory, that I quote Dr.
Cloos at length:
There are two rims to the African continent. Twice the funda-
mental problem arises: why do the continents of the earth end so
abruptly and plunge so steeply into the deep sea? . . . Even more
astounding, what is the meaning of the high, raised and thickened
mountain margins that most continents have? (85:68).
. , . The short cross-section through the long Lebombo Chain
looks unpretentious, but it illuminates events far from this remote
plot of the earth. For here the old margin of the continent is ex-
posed. Not so long ago, during the Cretaceous Period, the sea ex-
tended to here from the east. The flatland between the Lebombo hills
and the present coast is uplifted sea-bottom. . . . What we see are
the flanks of a downward bend of High Africa toward the Indian
Ocean. . . .
144 EARTH'S SHIFTING CRUST
But we see much more: the sedimentary strata are followed by
volcanic rocks to the east of the hills. Some parallel the strata like
flows or sheets, poured over them and tilted with them. Others break
across the sandstone layers and rise steeply from below. This means
that as the continent's rim was bent downward at the Lebombo hills,
the crust burst, and cracks opened through which hot melt shot up-
ward and boiled over.
So the eastern margin of Africa at the turn of the Paleozoic Period
was a giant hinge on which the crust bent down, to be covered by
the ocean. What we see here is merely a cross-section . . . one can
go further north or south, and even to the other side of the continent
and discover that great stretches of this unique land have suffered
the same fate. The oceans sank adjacent to the continents, and the
continent rose out of the ocean (85:73-74).
Cloos makes it clear that in one geological period the
continent was bent down so that a part of it became sea bot-
tom (not merely continental shelf) and that at a later period
it was uplifted some 6,000 feet, the sea bottom became land,
and the continental margin was shoved far to the east. When
we contemplate gigantic movements of this sort, it seems
reasonable to take the geophysical objections to changes in
the positions of the continents with a grain of salt. If a large
part of a continent can be shown not to have been perma-
nent, it is unnecessary to assume the permanence of any of it.
On the other hand, such changes need to be explained, and
they need to be reconciled with basic principles of physics.
The fact that theories of continent formation and history
hitherto proposed have failed to solve the problem reduced a
recent writer on lost continents to the following confession of
ignorance:
Since somebody can bring good, solid objections on one ground or
another against all these hypotheses, however, we had better agree
that nobody knows why continents or parts of continents sink, and let
it go at that. No doubt a sound explanation, perhaps combining fea-
tures of the older theories, will be forthcoming some day (64:161).
It may be useful to consider, in juxtaposition, the African
Rift with the question of the North Atlantic land mass al-
ready discussed. In a sense, the two are complementary. In
CONTINENTS AND OCEAN BASINS 145
one case a continent apparently subsided; in the other it first
subsided and then was raised up. Quite obviously the move-
ments in both directions must have been related to one
fundamental dynamic process. The physical geology of the
Rift, which can be directly examined, shows that the indirect
evidence of the sedimentary rocks of the northeastern states
of the United States, and of Scotland and Spitsbergen (and
the paleontological evidence), must be taken seriously. The
evidence in favor of an important land mass in the present
North Atlantic cannot be dismissed.
5. The Evidence of Oceanography
A great deal of new evidence bearing on the question of the
permanence of continents and ocean basins has resulted from
the oceanographic research of recent years. There has been a
revolution in our ideas of the nature of the ocean floor.
Formerly, it was thought that the ocean floors were continu-
ous, flat marine plains, buried thousands of feet deep under
an accumulation of sediments extending back in unbroken
series to the earliest geological periods. After all, the theory
of permanence of the ocean basins required this concept. It
has been found, however, that, on the contrary, there are
hills, valleys, mountain systems, and canyons on the sea bot-
tom very much like those on land. There is no continuous
thick layer of sediments. The features of the ocean bottom
appear to resemble, in singular fashion, those of the land.
One of our leading geologists, Richard Foster Flint, has
written:
Sound-wave surveying . . . has revolutionized our picture of the
ocean floor. Instead of the plainslike surfaces that were once believed
to be nearly universal, broad areas of the floor are now known to have
an intricacy of detail that rivals that of complex land surfaces. In
some places the detail seems to have resulted from local warping and
faulting of the crust and submarine volcanic activity, but in others it
consists of valley systems somewhat like those that diversify the land.
146 EARTH'S SHIFTING CRUST
Geologists are not agreed as to whether these features are valley
systems cut by streams and later submerged or depressions excavated
by currents beneath the sea (155).
Now this problem must be examined as a whole. Certain
facts are now obvious and can be plainly stated.
In the first place, if a continent can be lifted up a mile,
and the sea floor exposed, as in the case of Africa, surely it
can also be let down. Thus there is no reason for anyone to
lose his temper at the idea that some of these drowned sur-
faces were once above sea level. On the other hand, it is not
necessary to claim that they were in all instances eroded
above sea level. We saw, in the last chapter, that the basic
processes of mountain formation, folding, faulting, and vol-
canism, are of a kind that can take place just as well below
as above sea level. The only factor in mountain formation
that is mainly operative on the land is erosion, and that is,
as we have seen, a secondary factor.
Secondly, one of the most impressive arguments in favor
of the permanence of the ocean basins is that almost all the
sedimentary rocks that compose the continents appear to be
made of sediments that were laid down in comparatively
shallow water, on or near the continental shelves. We have
already seen, however, that parts of continents (at least) have
been submerged to great depths, and that parts of the deep-
sea bottom have been uplifted to form land. Why, then, have
rocks composed of typical deep-sea sediments not been found?
A number of factors may account for this. The primary
factor may be the rate of sedimentation. In the deep sea this
is extraordinarily slow— as low as one inch in 2,500 years.
Near the coasts it can be hundreds of times more rapid.
The theory presented in this book provides a mechanism
that would tend to operate against the consolidation of this
deep-sea sediment into rock. Frequent displacements of the
crust of the earth would naturally be accompanied by in-
creased turbulence on the ocean bottom, by which sediments
would be dispersed and mixed with other sediments. There
has been in recent years a great extension of our knowledge
CONTINENTS AND OCEAN BASINS 147
regarding the operation of turbidity currents (137, 139, 141)
caused by the slumping of sediments from the continental
slopes, and by other forces. It seems that such currents, even
now, are powerful enough to bring about considerable re-
arrangement of the unconsolidated sediments of the ocean
bottom. A displacement of the crust would greatly magnify
their force, for it would cause extensive changes in the direc-
tions of major ocean currents, changes in sea and land levels,
extensive volcanism in the sea as well as on land, and an
increased number and a greater intensity of earthquakes,
which would occasion extensive slumpings of sediments along
the continental slopes. If we consider that one such displace-
ment would, in all probability, keep the turbulence at a high
point for several thousand years, we can conclude that the
resulting dispersal of deep-sea sediments would probably be
on a considerable scale.
Finally, since we cannot suppose that any area would be
uplifted rapidly from the deep sea to the surface (that is, all
the way in the course of a single displacement), it follows that
in most cases deep-sea sediments would be raised into shallow
water, where they would be exposed for a long time in an
unconsolidated state to the erosive action of the much more
rapid currents near the surface before they would be likely
to be raised above sea level. A very small proportion of deep-
sea sediment would then be mixed by the currents with a
large proportion of sediment typical of shallow seas, and
would, in most cases, entirely disappear. These factors to-
gether dispose of this argument for the permanence of ocean
basins.
Another interesting line of evidence with respect to this
problem is provided by the recent discovery on the bottoms
of the oceans, already mentioned, of several hundred moun-
tains of varying heights, which have been given the name of
"sea mounts." These have the common characteristic of be-
ing flat-topped. Apparently, their tops were made flat by the
action of the sea at the time they were at the sea level. Now
148 EARTH'S SHIFTING CRUST
the flat tops are submerged anywhere from a few hundred
feet to three miles below sea level.
When these sea mounts were first discovered, they were
explained in accordance with the theory of the permanence
of ocean basins (210). It was proposed that as the sediments
gathered in enormous thickness on the ocean floor through
hundreds of millions of years, the floor actually gave way,
and sank, taking the sea mounts down below sea level. This
theory was undermined, of course, by the discovery that no
such thick layer of sediments exists on the ocean floors, but
that, on the contrary, the layer of sediments is in some places
extremely thin, or even virtually nonexistent.
Another line of evidence helps to dispose completely of
this explanation of sea mounts. Foraminifera are minute pro-
tozoa that live in the sea. Their species vary with differences
in the depth and temperature of the water in which they live,
and those of past geological periods, found in fossil state,
differ from living species. Studies of fossilized foraminifera
from the tops of the sea mounts have revealed that they are
much younger than the sea mounts have been assumed to
be (197). Comparatively recent species have been gathered
from the tops of sea mounts subsided to great depths. Unless
turbidity currents could suffice to carry such deposits long
distances across the ocean floor and then upwards to the tops
of the sea mounts, another cause for the subsidence of the
sea mounts must be found. When we remember that Umb-
grove referred to frequent upward and downward oscillations
of the floor of the Pacific, resulting from an unknown cause,
we can see that the idea of a gradual and continuous sub-
sidence of the ocean floor under the weight of accumulating
sediments is a singularly weak one, for even if the supposed
layer of sediments existed, the theory still unaccountably
ignores the recurring uplifts of the sea bottom.
The foregoing considerations reveal the essential weakness
of the conclusion that the seas that periodically invaded the
continents were always shallow seas— "epicontinental" seas,
flooding the permanent continents. First there was land;
CONTINENTS AND OCEAN BASINS 149
then, no doubt, shallow seas; after that, in some cases, very
deep sea, then again shallow sea, and finally again land, all in
the same place. But the interludes of deep sea may have been,
in many cases, very short, and the sedimentation resulting
may have never been consolidated. Thus the deep sea could
come and go, and nobody the wiser. New evidence bearing
on this problem is now available as the result of recent Soviet
oceanographic work in the Arctic. Soviet scientists have
found evidence that the Arctic Ocean itself has existed only
since the comparatively recent Mesozoic Era (364:18). We
shall return to this evidence.
It seems reasonable to conclude that at least some of the
problems presented by the continents and ocean basins are
soluble in terms of the principles described in this and previ-
ous chapters. Land links may be explained as the conse-
quences of mountain formation on the sea bottom; tempo-
rary and limited uplift or subsidence of large areas may result
directly from their poleward or equatorward displacement.
The major changes, however—the enormous elevations and
subsidences, the destruction and creation of continents—re-
quire us to examine the deepest possible consequences and
implications of crust displacement. We must now undertake
this deeper examination. This requires us to take another
glance at the nature and structure of the crust of the earth,
to its full depth, as far as our present geophysical knowledge
permits.
6. The Deeper Structure of the Earth's Crust
It has, until lately, been the impression that the earth's crust,
considered as a crystalline layer between 20 and 40 miles
thick, was itself composed of various layers, with rocks of
increasing density at increasing depths. This would have
been a natural development with a cooling earth, for it might
be supposed that the lighter materials in a liquid would tend
to float on the heavier ones, and would solidify in the order
150 EARTH'S SHIFTING CRUST
of their density, with the lightest on top. Daly, in 1940, pro-
posed the following layering of the crust, at least under the
continents:
a. The sedimentary rocks, at the surface.
b. Below these a layer of basement rocks of granitic type,
ending about 15 kilometers, or 9 miles, down.
c. A third layer of rock, of somewhat greater weight, about
25 kilometers, or 15 miles, thick.
d. A fourth layer, about 10 kilometers, or 6 miles, thick, of
still heavier rock.
Having proposed these layers, however, he added that "the
exact depths of the discontinuities are not easily demon-
strated" and "it seems clear that each of the breaks varies in
its depth below the rocky surface" (97:17). In another place
he gave evidence of light matter at the very bottom of the
crust (97:223). These layers, then, according to Daly, are very
peculiar. There is nothing regular about them. On the one
hand, he gives rough estimates of their thicknesses. On the
other hand, he indicates that these estimates are of little
value. They are, in fact, mere rough averages; they indicate
a trend toward increasing density with depth, together with
enormous confusion in the distribution of materials.
In view of the extreme uncertainties of Daly's view of the
structure of the earth's crust, it can hardly come as a com-
plete surprise that the most recent geophysical investigation
of the structure of the crust by the method of sound-wave
surveying has failed to show any distinct layering of the
crust. The geophysicists Tatel and Tuve have reported that
the results of the most recent studies, using the most recent
techniques, indicate that rocks of greater or less density are
intermixed in utter confusion, that the essential structure
of the crust is really that of a rubble, on a large scale (416:
107).
The main argument of the geophysicists who speak in
favor of the permanence of the continents, and, consequently,
of the ocean basins, is based on the observed difference in
CONTINENTS AND OCEAN BASINS 15!
composition of continents and of the crust under the
oceans, a difference that has been verified for the uppermost
few miles of the continental and oceanic sectors of the crust,
but not for the greater depths.
Now, if everything below, say, a depth of ten miles were
layered everywhere at equal depths with rock of equal
densities, no quarrel whatever could be had with the geo-
physicists who argue for the permanence of continents and
ocean basins. For in that case, only a massive change in the
distribution of the superficial layers of light and heavy rock
could change the distribution of continents and ocean basins.
Granitic or sedimentary rocks at the surface .would have to
be destroyed or created in enormous quantity to destroy or
create a continent.
It is entirely otherwise with the structure as suggested by
Daly and as revealed in the recent geophysical surveys. To
understand this it is necessary only to visualize that the rela-
tive elevation of the surface at any point is determined by
the average density of the entire column of matter between
the surface at that point and the bottom of the crust, where,
presumably, the inequalities at different points are pretty
well averaged out.
If the crust is not definitely layered, if, as both Daly and
recent geophysicists agree, there are radical variations in the
structure, then the vital changes may occur at any depth,
deep down as well as at the surface. There is reason to be-
lieve that massive changes may occur more easily deep down
than at the surface. Thus, the crust might be weighted in its
lower parts by an intrusion of a great mass of molten rock
of high density from below, a very likely result of a displace-
ment. In either case, whether the addition of the heavy mat-
ter occurred near the surface or far below it, the result would
equally have been a depression of the surface, with a con-
sequent encroachment of the sea. Obviously, a repetition of
such movements could subside a continent to a great depth,
without altering the composition of the superficial forma-
tions.
152 EARTH'S SHIFTING CRUST
On the other hand, a shifting of the masses of lighter rock,
which might have formed the downward projections of con-
tinents and mountain chains, as the result of a displacement,
could lighten certain sectors of the crust and result in their
uplift.
That rocks of light weight are to be found at the very
bottom of the crust (and even in the downward projections
under continents and mountain chains that extend to greater
depth) might, as a matter of fact, have been deduced from
Daly's observation that the process of mountain folding has
involved the whole depth of the crust, and not just its surface
layers (97:399)- His suggestion is that since the folding of
the crust to form mountain ranges involves its horizontal
shortening, the horizontal shearing movement has to take
place at the level where displacement will be easiest, which
will be at the bottom of the crust where the rock has mini-
mum, or zero, strength. For it is plain that at a level at which
the rock possessed any considerable tensile strength, the
shearing of one layer over another horizontally would be
practically out of the question.
It would seem, from these considerations, that the com-
monly used terms "sial" and "sima" to differentiate lighter
from heavier material in the crust, especially when they are
presumed to indicate different layers, have very little mean-
ing. They amount to trends merely, and take no account of
the detailed distributions of the materials of different density
either vertically or horizontally. It would be wrong, there-
fore, to assume that just because we find a layer of basalt on
the floor of the Atlantic (as has been recently reported) this
layer necessarily extends to the bottom of the crust, and is
not underlain, at greater depth, by sedimentary and granitic
rocks of less density. It is even true that the layer of basalt
may have been extruded during the subsidence of the sea
bottom in the last movement of the crust, and have been,
in itself, one cause of the subsidence.
Jaggar, for one, considered that it was far more reasonable
to account for subsidence or elevation at the surface by
CONTINENTS AND OCEAN BASINS 153
changes of weighting deep in the crust than by erosion and
sedimentation at the surface. He remarked:
... It would seem possible that intrusive and extrusive processes
may lighten or weight the crust much more profoundly than the
movement of sediments (235: 153).
How, precisely, would these processes be apt to be set in
motion by a displacement of the crust? We saw that a dis-
placement would cause a general fracturing of the crust, the
creation of a new world-wide fracture pattern. In areas moved
toward the equator, the extension of the surface area would
involve some pulling apart of the crust, the separation of the
fragments, their subsidence into the semiliquid melt below,
and the rise of the magma into the fractures, with, at some
points no doubt, massive eruptions on the surface. Differen-
tial movements of blocks of the crust would occur as each
sought its gravitational equilibrium, some rising and others
subsiding. In areas moved poleward compression would be
the rule, with some folding of the crust, with block faulting
accompanied by tilting of larger or smaller blocks. In these
areas the strata of lighter rock would grow thicker, from
being folded upon themselves; in equatorward-moving areas,
on the other hand, they would tend to grow thinner, because
much of the lighter rock might be engulfed in the rising
heavy magma.
However, major changes in the situation of continents
require additional processes, even though changes such as
those suggested above might, if they accumulated over long
periods of time, produce very important results. The massive
changes, capable of subsiding or elevating continents, might
be of two different sorts, though both of them must, in the
nature of things, remain speculative for the present. One of
these would be the massive intrusion of immense quantities
of heavy magma into the crust (resulting finally in plateau
basalts). Such an effect could be produced by subcrustal cur-
rents set in motion by a displacement, and would have the
effect of causing a major subsidence at the surface. The other
cause of massive change in the average density of a given col-
154
EARTH'S SHIFTING CRUST
\
Fig. V.
Consequences of Displacement: Cross Section of Earth at 96°
East of Greenwich Showing Centrifugal Effect of Icecap
In Figs. V and VI the artist imaginatively suggests some consequences of
a displacement of the crust. On this page we see a cross section of the
earth before the movement, with the eccentric icecap above the equilib-
rium surface of the earth. On page 155 we see a cross section of the earth
after a displacement through about 30 degrees of latitude. The drawings
are not to scale. It has been necessary, for purposes of illustration, to
exaggerate the oblateness of the earth, the depths of the oceans, and
the thickness of the crust several hundred times. The drawings illustrate:
(i) The subsidence of the crust in areas displaced toward the equator,
relatively to sea level, and its uplift in areas moved poleward. (2) The
CONTINENTS AND OCEAN BASINS
155
Fig. VI. Consequences of Displacement: Cross Section of Earth at 96°
East of Greenwich Showing Hypothetical Effect of Shift of Crust
fracturing and tilting of crustal blocks, suggested schematically. It should
be understood that in reality the blocks would be comparatively small
and the fractures would be numbered in millions. (3) The displacements
of parts of the downward projections of the crust under continents and
mountain chains, which would have an effect on the permanent eleva-
tion of the surface relatively to sea level. (4) The volcanism attending
the movement, with the projection into the atmosphere of volcanic dust
capable of causing meteorological effects.
156 EARTH'S SHIFTING CRUST
umn of the crust (that is, a section extending from top to
bottom of the crust) would be a shifting of light matter from
one point to another under the bottom of the crust. This
matter was discussed in the last chapter. While in that chap-
ter relatively minor effects were considered, it is true, never-
theless, that the shifting of light matter from one point un-
der the crust to another could take place on a very large scale.
What might be the upshot of all these changes during a
displacement of the crust? The result might well be that
while the distribution of light and heavy matter near the
surface would be unchanged, its distribution (average den-
sity) between the surface and the bottom of the crust would
be materially changed. This is undoubtedly the direction in
which we must look for a solution of the problem of con-
tinents and ocean basins, as a means of reconciling geophysi-
cal ideas with the evidence of biology and geology.
I cannot close without reference to a singular confirmation
of the line of reasoning adopted in this chapter, which I find
in Umbgrove's discussion of the work of the geologist Barrell,
with whom he disagreed.
Umbgrove is considering the question of the submergence
of continents. It is clear from his discussion that Barrell's
conception of the process requires a theory of crust displace-
ment. Umbgrove states the problem thus: If we are to sup-
pose the submergence of continents, we must either suppose
a change in the amount of the ocean water, which, if it in-
creased, could flood a continent (or several at once), or, if the
water remained about the same in quantity, the submergence
of one continent must be balanced by the elevation of an-
other. He presents the findings of specialists to show that
the quantity of water on the earth's surface has remained
about the same, from the earliest times, and adds:
Should one, nevertheless, cling to the theory of submerged conti-
nents, the only alternative would be to assume that while vast blocks
were being submerged in one area, parts of the ocean floor of almost
identical size were being elevated in others. . . .
CONTINENTS AND OCEAN BASINS 157
It is not quite clear, however, why such opposed movements should
have occurred in areas of almost equal extent. Nor is it clear why
these movements should have occurred in such a way that the sea-
level remained comparatively stable. . . . (430:235-36).
But a displacement of the crust—or several displacements
—would fulfill all these requirements. In a displacement two
quarters of the surface, opposite each other, must move to-
ward the poles, while the other two quarters must move to-
ward the equator. Whatever forces tend to produce uplift in
the poleward-moving areas will be balanced by equal forces
producing subsidence in the quarters moving equatorward.
And the sea level would be stable, except for very minor
fluctuations.
Barrell himself suggests that subsidence of continental
areas would be aided by liquid intrusions, "the weight of
magmas of high specific gravity rising widely and in enor-
mous volume from a deep core of greater density into these
portions of an originally lighter crust. . . ." (430:235-36).
Barrell's suggestion points to the chief weakness of the
geophysical argument in favoi of the permanence of the con-
tinents. As I have already pointed out, geophysicists seem,
too often, to take as the frame of reference only the outer-
most ten miles or so of the crust. Theoretically they base
calculations on the full depth of the crust, but practically
this assumption is cancelled out by the assumption that the
crust is arranged in layers of equal density, so that significant
changes of density in depth are excluded. But if the real
possibilities of changes of average density in the full depth
of the crust are taken into account, the difficulties in the
face of the subsidence and elevation of continents vanish.
VI : THE SHAPE OF THE EARTH
In the two preceding chapters we have considered the evi-
dence for displacements of the earth's crust provided by
mountain chains, earth fractures, volcanic zones, continents,
and ocean basins. We have had occasion to refer, a number
of times, to the effects of the force of gravity, and of the
earth's rotation, on the earth's crust. The understanding of
the theory of crust displacement presented in this book de-
pends entirely on a correct understanding of these two forces,
and of the operation of what we call the principle of isostasy.
The ideas are not difficult, provided certain essentials are
kept in mind.
j. Isostasy and the Icecap
The globe we live on is shaped primarily by the force of
gravitation. The weight of the materials of which it is com-
posed is greater than their strength, and they have therefore
been bent, broken, or forced to flow by this force until the
globe has become a sphere. It is not, however, a perfect
sphere. The earth deviates from being a perfect sphere be-
cause it is rotating rapidly, and the rotation produces a cen-
trifugal effect that tends to throw the materials outward at
right angles to the earth's axis, and against the force of grav-
ity. This slightly modifies the earth's shape, producing a
bulge around the equator and a flattening at the poles. The
earth modifies its shape until the two forces are in balance,
and the resulting oblate sphere is called the "geoid."
Of course, there is always a considerable amount of shift-
ing of materials going on on the face of the earth, rivers
bringing down sediment to the sea, icecaps growing and
melting, and these changes are constantly upsetting the bal-
THE SHAPE OF THE EARTH 159
ance and requiring readjustments. The crust of the earth,
being very thin as compared with the whole diameter of the
globe, is correspondingly weak, and usually gives way if much
material is accumulated on it at any one spot. The layer
under the crust is considered to be quite weak, and it per-
mits the crust to give way by flowing out from under. This
process is called "isostatic adjustment/' Funk and Wagnalls
define isostasy as follows:
Theoretical condition of equilibrium which the earth's surface
tends to assume under the action of terrestrial gravitation as affected
by the transference of material from regions of denudation to those
of deposition, and by difference of density of various portions of the
earth's mass near the surface.
In the last chapter we considered at length the effects of
the differences of density of rocks under oceans and con-
tinents, and how heavy rocks tend to reach equilibrium at
lower elevation, and lighter rocks tend to be found in con-
tinents and mountain chains.
According to the principle of isostasy, it has been widely
assumed that an icecap such as the one in Antarctica should
be in good isostatic equilibrium. Of course, if this were true,
the centrifugal effect of the icecap would be balanced at
every point by the force of gravity, and there would be no
effect left over to tend to shove the crust over the plastic
layer below. There might be a slight effect resulting from
the elevation of the continent and the icecap above the
mean earth surface, but it would be too small to consider.
Thus, our theory depends upon our ability to show that
isostasy has not operated effectively in Antarctica. The ques-
tion becomes one of estimating the difference between the
rate of growth of the ice sheet, the rate of yield of the crust,
and the rate of flow of the plastic layer under the crust. The
calculation must also take account of the amount of load
that may be borne by the crust, indefinitely, out of isostatic
adjustment, because of its degree of tensile strength. Camp-
bell's calculations of the centrifugal effect of the icecap, and
of the resulting bursting stress on the crust (Chapter XI),
160 EARTH'S SHIFTING CRUST
are based on the assumption that the whole mass of the ice-
cap is uncompensated. They are only approximations, and
must be modified as soon as more information as to the de-
gree of the isostatic adjustment of the icecap is available.
On the other hand, it does not necessarily follow that the
gravity measurements to be taken in Antarctica during the
coming year will be able to provide a definite answer to
the question. It is obvious that the theory of isostasy is at pres-
ent under considerable attack, and that differences of opinion
exist as to the validity of the various methods of interpreting
the findings about the gravitational balance of the crust.
Daly himself remarked that probably none of the present
methods for determining the degree of isostatic adjustment
of a crustal sector was capable of getting very close to the
truth. A far more serious attack on the theory was made some
time ago by Hubbert and Melton. They pointed out that
all methods of reducing gravity data to measure isostatic
compensation depend upon assumptions regarding the dis-
tribution of materials in the earth, which must be regarded
as essentially unknown (226:688). They conclude:
The fields providing data on the subject of isostasy are geodesy
[measurement of the shape of the earth], seismology [study of patterns
of earthquake waves], and geology. The data of the first, which until
recently have provided the main support of isostatic theory, have
been shown by Hopfner to be invalid. The data of the second have
only an indirect bearing on the question. The data of the last are
more often than not contrary to isostatic expectations. Hence, the
theory of isostasy must for the present be regarded as resting upon a
none too secure foundation, and it is hardly trustworthy for use as a
major premise in present discussions of earth problems (226:695).
In the following pages I shall proceed on the assumption
that the isostatic principle is generally correct, even though
present methods of measurement are unsatisfactory. I shall
assume that the materials of the earth's surface are under
constant gravitational pressure to conform to the ellipsoidal
shape of the earth, and that this applies to the icecap, and
will bring about a tendency of the crust under the icecap
THE SHAPE OF THE EARTH l6l
to yield and sink, displacing soft rock from below as the ice-
cap grows in weight. At the same time I should like to pre-
sent a number of considerations indicating that there is, at
the present time, a massive departure from isostatic equi-
librium in Antarctica.
One of the most astonishing things revealed by the new
techniques of radioelement dating is, as we have seen, the
rapid rate of the growth both of the present ice sheet in
Antarctica and of the last great icecap in North America.
Even before the new knowledge was available, however,
various authorities had agreed that there must be a consid-
erable lag between the growth of an ice sheet and the adjust-
ment of the crust to it by subcrustal flow of the plastic rock
out from under the glaciated tract. The geologist Wilhelm
Ramsay, referring to this lag, said:
... As the icecaps grew bigger and thicker, they loaded more
and more the areas occupied by them. The crust of the earth gave
way, and began to sink, but not in the proportion that the loads
increased (352:246).
Ramsay pointed out that the "rebound" of the crust follow-
ing the removal of the ice still continues thousands of years
after the end of the ice age, showing how slowly the crust
adjusts. Daly also referred to this lag:
Owing to the stiffness of the earth's materials and the sluggish-
ness of their response to deforming forces, the basin [around the
Baltic] persisted long after the ice melted away. The lower parts of
Scandinavia and Finland were kept submerged under the sea. . . .
(97^90).
According to Daly, the present isostatic distortion in the
center of the area once occupied by the great Scandinavian
ice sheet is the equivalent of "a plate of granite with a
thickness of 160 to 270 meters of rock" (97:386-87). This
amounts to about three times as much ice. Thus it would
amount to an ice sheet between 1,500 and 2,500 feet thick,
and this in spite of the fact that isostatic adjustment has
theoretically been proceeding in that area for perhaps 15,000
i6s EARTH'S SHIFTING CRUST
years. If we assume that the lag was the same during the
growth of the icecap, we can see that there may have been
an enormous excess of matter on the crust when the Scandi-
navian icecap reached its apogee.
In another way, Daly shows how slowly the compensating
flow that permits adjustment takes place. He refers to the
fact that erosion from a continent or large island appears to
create negative anomalies (deficiencies of mass) on the land
and positive anomalies in the sea (97:297-98). This is so
because the crust does not adjust as rapidly as erosion takes
place. Yet we can easily see that the accumulation of ice is
faster than the weathering of rock and the deposition of
sediments in the sea.
The geophysicist Beno Gutenberg has made a number
of statements that strongly support the same conclusion. In
discussing the zone within the earth where adjustment is
carried on, he says:
... It is inferred that this depth represents (in geologically
stable regions) the critical level below which strain is nearly reduced
to zero by subcrustal flow in periods of, say, 100,000 years (194:316).
The period of 100,000 years indicated by Gutenberg ap-
pears to be a multiple of the time required for the growth of
a vast continental icecap. In another place, he refers directly
to the lag between the growth or retreat of an ice sheet and
the adjustment of the crust. After listing other ways in which
the isostatic balance of the crust may be disturbed, he adds:
A probable instance ... is the lag in complete compensation
of the load provided by the Pleistocene ice sheets. This is shown by
the recoil of the tracts unloaded by the melting of the ice (194:319).
He remarks, further:
The processes by which isostasy is maintained must be extremely
slow, and consequently, this equilibrium is liable to disturbance by
geological events (194:318).
Gutenberg and Richter, in their volume on The Sets-
mici'y of the Earth, express the known facts about adjust-
THE SHAPE OF THE EARTH 163
ment within the rigid crust itself. They remark: ". . . it
requires several thousand years for the strains due to the re-
moval of the ice load to be reduced to half" (195:101). This
and the preceding statements may serve to establish the rea-
sonable presumption that any icecap, at the height of its
rapid accumulation, must be largely uncompensated.
But even if, during the rapid growth of the present An-
tarctic icecap, a degree of isostatic adjustment has taken
place, this does not end the matter for us. We must ask,
Where does this plastic rock go? Presumably it flows out,
under the crust below the ocean bed, beyond the fringes of
the ice-covered continent, at a depth of twenty to forty miles
below the surface of the earth. It may raise the crust some-
what for a distance beyond the edges of the ice sheet. Dr.
Harold Jeffreys gave it as his opinion that, if a gravity survey
of Antarctica should be undertaken, we might expect to
find marked positive anomalies around the coasts (241). But,
since in general the plastic rock under the crust is not flowing
into any area of deficient mass, the flow, upraising the coasts
or the sea bottoms off the coasts, must still constitute excess
matter, and must exert a centrifugal effect about equal to
the former effect of the ice that has now been brought into
equilibrium.
Let us consider this point a little further. We have noted,
above, that according to the definition of isostasy, the process
is a response to the transfer of material from one region to
another: sediment is removed from an area of "denudation"
and transferred to an area of "deposition." The area of dep-
osition, then, sinks under the load, and a flow of rock under
the crust moves back to the area of denudation, compen-
sating for the material that has been removed, and restoring
the equilibrium. But where can the plastic rock displaced
by the icecap flow? No adjacent area ha$ been lightened by
the removal of sediment; the plastic rocK must, then, wher-
ever it flows, create a distortion, a surplus of matter, which
will have a centrifugal effect.
From the standpoint of the theory presented in this book,
164 EARTH'S SHIFTING CRUST
it makes no difference whether the excess mass that creates
the centrifugal effect is constituted of ice or whether it is in
part constituted of rock. It may be concluded, therefore, that
the isostatic process itself is ineffective in counteracting the
centrifugal effects of icecaps.
We may conclude, then, first that the rate at which isostasy
may work is too slow to keep up with the deposition of the
ice; and second, that in so far as it does work it will not elimi-
nate the centrifugal effect of the uncompensated mass, but
will merely substitute rock for ice.
2. The Antarctic Icecap Is Growing
The theory presented in this book requires, of course, that a
polar icecap should grow, and continue to grow, though not
perhaps steadily, until it is big enough to move the crust. In
this connection it is important to examine certain current
ideas about the Antarctic icecap.
It is widely believed that the Antarctic icecap, like some
ice fields in the Northern Hemisphere, is in recession, and
was once greater than it is now. This is a mistaken impres-
sion, the error of which can be easily shown, even without
any more data from Antarctica. I will venture to remark,
indeed, that any further data from that continent are likely
to show that the icecap there is in a phase of rapid expansion.
I will begin with the northern ice fields, about which more
is known. There is no doubt that most of them are melting,
but the exceptions are very significant. These include the
Greenland icecap, which appears to be holding its own
(after having considerably expanded since the Viking settle-
ments there during the Middle Ages), and the Baffinland
icecap, which is growing. The mountain glaciers of the Amer-
ican northwest have, apparently, started a readvance (329).
The most important fact regarding those northern ice fields
that have been in retreat is that their retreat began only
about the year 1850, and that, before that, they were expand-
THE SHAPE OF THE EARTH 165
ing generally for about 300 years. Between 1550 and 1850
the old Viking settlements in Greenland were overwhelmed
by the advancing ice. From this it follows that the present
trend in the northern ice fields is not a long-term trend, but
only an oscillation. Therefore, it must not be deduced that
we are just getting out of a glacial period, and that all ice
fields are retreating and will continue to retreat.
Recent weather research has made it plain that alternating
climatic phases of slightly colder or warmer temperatures
have been the rule for some thousands of years. Such phases
would have no connection with any movement of the earth's
crust, but are probably related to varying atmospheric fac-
tors, such as slight variations in the amount of volcanic dust
in the air, or short-term sunspot cycles. It is known that the
warmest phase of the climate, since the ice age, occurred
between 6,000 and 4,000 years ago. This did have a connec-
tion with the most recent displacement of the crust, as I will
show later on. This warm period is in itself sufficient evi-
dence that there has been no steady warming of the climate
since the icecaps melted.
It is even true that a slight warming of the climate, such
as appears to have occurred since about 1850, may increase
precipitation of snow on the Antarctic continent. This sug-
gestion has been advanced by a number of meteorologists. It
is based on the following reasoning: The Antarctic average
temperature is much colder than that of the Arctic. A slight
warming of world temperatures will increase the amount of
the humidity in the atmosphere. In northern regions, the in-
creased humidity in the world's atmosphere may result in
increased rainfall, while in Antarctica, because of the lower
temperature, the increased precipitation may mean increased
snowfall.
Up to the present time, only one impressive body of evi-
dence has been produced to prove that the Antarctic icecap
has receded from a former greater extent. This evidence con-
sists of numerous indications of ice action on the barren
sides of Antarctic mountains as much as 1,000 feet above the
i66 EARTH'S SHIFTING CRUST
present levels of the ice. As matters stood before the develop-
ment of nuclear methods of precision dating, this evidence
appeared conclusive. It certainly argued strongly that the
icecap was greater in the past.
We are now able to take a different view of the matter.
Now we know that this icecap is largely of very recent growth.
We know, too, that before a preceding temperate age in
Antarctica there was another icecap, and that there were
several icecaps during the comparatively short period of the
Pleistocene alone. We can assume, moreover, that the ice
centers of the different ice sheets were in different places, so
that the distribution of the ice— its thickness in different
places— would be different from now, even if the total amount
of ice were about the same. (See Figure VII.)
If the question is asked, Cannot we tell from the appear-
ance of the striations, and other evidences of ice action on
the Antarctic mountainsides, how long ago they were made?,
the answer is No. The processes of weathering and erosion
in Antarctica are slow. The striations, even if they were very
old, could look as if they were made yesterday. Henry, in the
White Continent, discussing the visit of Rear Admiral
Cruzen in 1947 to a camp at Cape Evans that had been aban-
doned by Scott more than thirty-five years before, throws
some light on this peculiarity of Antarctica:
. . . From the camp's appearance, the occupant might have left
only within the past few days. Boards and rafters of the cabin looked
as if they had just come from the saw mill; there was no rot on the
timbers; not a speck of dust on the nailheads. A hitching rope used
for Manchurian ponies looked new and proved as strong as ever
when it was used to hitch the helicopter. Biscuits and canned meats
still were edible, though they seemed to have lost a bit of their
flavor. A sledge dog, which apparently had frozen to death while
standing up, still stood there looking as if it were alive. A London
magazine, published in Scott's day and exposed to the elements since
his departure, might have been printed that morning (206:44).
The same factors— intense cold, with absence of the destruc-
tive process of alternate melting and refreezing, and absence
THE SHAPE OF THE EARTH 167
of water action, and the absence of minute organisms— would
preserve indefinitely the freshness of the glacial evidences.
If there are any who still hesitate to accept the evidence of
several successive ice ages in Antarctica during the Pleisto-
cene, let them remember that we recognize four in North
America and in Europe during that period, and that even
here it is not always easy to assign glacial evidences to the
correct glaciation.
Once it is fully recognized that the geological evidence of
Antarctic ice recession must be reinterpreted, we are in a
better position to evaluate the large mass of evidence now at
hand regarding the present accumulation of snow in Antarc-
tica. Geologists have hesitated, because of the earlier evi-
dence, to interpret the data at all. Among the important
items of information are the following: Henry mentions evi-
dence of an accumulation of 18 feet of snow in seven years
on the Antarctic barrier ice (206:75). The party that visited
Antarctica on the icebreaker Atka in 1954 found evidence of
the accumulation of 60 feet of snow at one spot since 1928:
One of the Atka's three Bell helicopters took off with Commander
Glen Jacobsen, the ship's captain, as observer. It landed at the 1928
camp and found that one of the three towers was completely buried
in snow although it had originally stood more than 70 feet high. The
two others barely showed above the drifts (411).
In 1934, when Byrd made his second trip to Antarctica, he
found that the Ross Shelf ice had encroached 1 2 miles on the
sea since Scott charted it in 1911 and that there was much
more ice in the Bay of Whales than when Amundsen visited
it in 1911-13. Recently, Bernhard Kalb wrote in the New
York Times:
. . . Little America II— the 1933-35 base— had been built directly
on top of snow covered Little America I— the 1928-30 base. But the
last twenty years of snowfall had obliterated that base, too. The only
reminders that there is a sort of Antarctic Troy entombed in the
Ross Sea shelf— a spectacular table of glacier-fed ice floating in the
sea, three times the size of New York State— were two steel radio
towers and the tops of half a dozen wooden antenna poles. The towers,
168 EARTH'S SHIFTING CRUST
dating from 1929, had been seventy feet high; now less than ten
feet of them could be seen (246:59-60).
The best evidence for the rate of snow accumulation in
Antarctica, however, comes from some scientific measure-
ments taken in connection with "Operation Highjump" by
the United States Navy, in the years 1947-48. The reports of
this thorough study were included in the Army Observer's
Report of the expedition, and were made available to me
through the kindness of Admiral Byrd. Observations were
made at a number of points; the snowfall was found to have
averaged nine inches per year since the previous Byrd expedi-
tion (12).
Of course, snow does not accumulate equally at all points
in Antarctica. In many exposed places it may not accumulate
at all, but may be blown away by the wind. In the interior it
is reasonable to suppose it may accumulate at a slower rate
than on the coasts. Since measurements taken in a few areas
only may be seriously misleading, we should briefly review
the general factors controlling the snowfall and snow accu-
mulation.
First, let us cite the testimony of a scientist-explorer, Nor-
denskjold, who was the first to take scientific measurements
of the snowfall in Antarctica. He also took temperature rec-
ords during many months. Of these he said:
They also prove that there is a tremendous difference between
an arctic and an antarctic summer climate, and that our summer
was colder than winters in southern Sweden. But the temperature
alone does not give a true idea of the conditions in South Polar
regions, and the following example will serve to illustrate some
other points of view. I had arranged a row of bamboo rods on the
glacier, in order to measure the changes in the height of the ice caused
by thawings and snowfalls. During the winter this height was found
to be constant, and not the slightest part of the snow which then fell
remained on the glacier. But during the summer, on the other hand,
the height of the snow covering increased by 25 centimeters (9.75
inches) and this amount still remained when we left these tracts one
year later.
Thus the reader must imagine a climate where winter is as severe
THE SHAPE OF THE EARTH 169
as winter in western Siberia, and so stormy that every particle of
snow blows away; where the summer, even in the low latitudes
where we were, is as cold as near the North Pole, and is, moreover,
such that snowdrifts and glaciers increase during the warmest season
of the year (335- 253-54)-
Nordenskjold's camp, where he took these observations,
was, apparently, about 64° S. Lat., or more than a thousand
miles from the pole.
From this account it is evident that while a little melting
may occur from time to time in Antarctica (and some has
been recently reported), such melting must be entirely in-
consequential. As to the quantity of precipitation over the
whole continent, the following considerations seem impor-
tant. First, the low temperature means a comparative lack of
humidity in the air; precipitation could not equal that in
temperate or tropical regions, for cold air will not hold as
much moisture as warm air. Second, wind pattern and topog-
raphy are both important factors. The wind pattern is as
follows: There are winds blowing toward the pole at high
elevations; these have, of course, crossed oceans on their way
to the pole, and have picked up moisture. As they approach
the pole they are compressed and chilled, and they contract
and lose moisture in the form of snow. The air, now having
greater density, sinks to the ice surface and moves outward in
anticyclonic pattern. Winds blow outward in all directions
from the pole, bearing with them great quantities of snow.
Much of the snow is borne out to sea, but much is deposited
in every nook and cranny, in all declivities, and, from the
beginning of the growth of the icecap, the fringing coastal
mountain chains have aided in the storage of snow. They do
not prevent the high-altitude winds, bearing their moisture,
from entering the continent, but they do, naturally, interfere
to some extent with the outward-flowing, low-altitude winds,
forcing them to deposit snow.
Now, these conditions have naturally been the same since
the beginning of the growth of this continental icecap, and
they must have prevailed with the previous icecaps. But we
170 EARTH'S SHIFTING CRUST
see that the icecap has accumulated nonetheless, and that it
is now accumulating. Thus we can safely conclude that these
anticyclonic winds have not prevented, and can never prevent,
the continuing growth of the ice sheet.
One other factor may limit the accumulation of ice. Ice-
bergs break off from the icecap every year in great numbers,
and it has even been suggested that they may amount to
roughly the entire annual deposition of snow upon the conti-
nent. How far this is from representing the true state of
affairs can be determined from the following considerations.
In the first place, the icebergs form, it is generally agreed,
because the ice sheet is flowing slowly outward from the pole
in all directions, by the effect of gravity. The ice has accumu-
lated in the central area of the continent to a great but as yet
unknown depth, and from this central area the surface of the
ice sheet slopes gently downward toward the coasts. It is
recognized that what sets the ice sheet in motion is not the
slant of the land it lies on (it would move even if the land
were all flat) but the angle of the slope of its own surface:
the gradient (87:46). This being the case, two factors govern
the speed of movement: the more gradual the gradient, the
slower the ice flows, while the colder the ice, the greater its
viscosity and its resistance to movement. Now, in Antarctica
it has been observed that the gradient is only one third of the
gradient in Greenland, where, despite a more rapid move-
ment of the ice, the glacier still maintains itself approxi-
mately in a static condition. The Antarctic, in addition, is
much colder, and therefore its ice is more viscous, more rigid,
more resistant to motion. What the temperatures deep in the
icecap are is at present unknown, but they are probably con-
siderably lower than those in the northern glaciers. Coleman
notes how much slower is the movement of ice in Antarctica
than it is in Greenland (87:44). (See n. i, p. 192.)
Brown has correctly pointed out that a large production of
icebergs, such as we note in Antarctica, is a sign of an expand-
ing glacier, while a dwindling supply of icebergs is evidence
of an icecap in decline (54). Einstein was of the opinion that
THE SHAPE OF THE EARTH 171
the flow-off of icebergs could not even be an important factor
in reducing the rate of the annual increment of ice on the
glacier (128). The general problem of the Antarctic icecap
may be summarized thus:
First, we know that there is never any considerable melting
of snow in Antarctica. We have radioelement evidence of an
enormous expansion of the icecap there in recent millennia.
We also have evidence that it is now accumulating. We can
add that studies carried out by Captain Charles W. Thomas,
of the United States Coast Guard, of the radiolaria (minute
organisms) contained in samples of bottom sediments from
the Antarctic have recently convinced him that * 'during the
last 5,000 years the waters surrounding this continent (Ant-
arctica) have been getting colder" (411) just as would have
to be expected with a growing icecap.
Secondly, if Antarctica has always been at the South Pole,
what conceivable factor could have operated to prevent the
formation of an icecap there until the comparatively recent
Eocene Period, only about 60,000,000 years ago? Once an
icecap had formed, what other factor could have interrupted
the glaciation, so as to bring about the growth of luxuriant
forests there in later periods? Since it has been shown that
climatic zones like the present have clearly existed during
the whole of geological history (Chapter III), would we not
be justified in expecting the icecap to have accumulated con-
tinuously in Antarctica at least since the first known pre-
Cambrian ice age, about two billion years ago?
Thirdly, Campbell has made the significant observation
that the Antarctic icecap never melts, yet we know that ice
sheets elsewhere on the globe have melted again and again.
It has proved impossible to account for the ice sheets that
once existed and melted away in areas now near the equator.
Campbell points out that even if the rate of snowfall in
Antarctica is low compared with the precipitation in warmer
climates, yet the icecap has, in the oceans, an unlimited sup-
ply. It follows that, if the present icecap is not large enough
172 EARTH'S SHIFTING CRUST
to start a movement of the crust, it will simply continue to
grow, drawing upon the endless resources of the oceans until
it is big enough.
3. A Suggestion from Einstein
From the foregoing, it is clear that there is a basis for the
presumption that the Antarctic icecap is largely an uncom-
pensated mass (an extra weight on the surface of the earth),
that it has grown continuously since the disappearance of
nonglacial conditions in the Ross Sea area only a few
thousand years ago, and that it is growing now. Einstein
recognized, in the Foreword to this book, the centrifugal
momentum that such an uncompensated mass, situated eccen-
trically to the pole, would create when acted upon by the
earth's rotation, and he saw that the centrifugal momentum
would be transmitted to the crust. But he also raised, in the
last paragraph of the Foreword, another interesting question.
If an icecap can have such an effect, so can any other uncom-
pensated mass. It is necessary to investigate any existing dis-
tortions within the crust itself and to learn whether it may
contain uncompensated masses of a magnitude comparable to
the Antarctic icecap, and thus capable of causing comparable
centrifugal effects. For the inference is obvious: if such masses
are in existence, but have not moved the crust, it follows that
the crust may be anchored too solidly to be moved by the
centrifugal effect of icecaps.
One of the troubles with the theory of isostasy is that the
failures of the crust to adapt to gravitational balance have
been found to be more numerous and more serious than ex-
pected. Daly lists and discusses a large number of them. It
appears, for example, that the whole chain of the Hawaiian
Islands, with their undersea connecting masses of heavy
basalt, are uncompensated (97:303). These islands rise from
the deep floor of the Pacific, and their peaks tower two and a
half miles above sea level. Their gigantic weight rests upon
THE SHAPE OF THE EARTH 173
the crust, and under the weight the crust has bent down
slightly, but it has not given way. This is the more remark-
able since the islands appear to be several million years old.
It indicates that at this point the earth's crust is strong
enough to bear a very considerable weight without yielding.
The Great Rift Valley of Africa, which we have already dis-
cussed, is uncompensated, despite its great age (97:221).
There are also enormous anomalies in the East Indies. Ac-
cording to Umbgrove, Vening Meinesz found that the nega-
tive anomalies (that is, the deficiency of matter) in the great
ocean deeps in that area and the positive anomalies on each
side caused a total gravity deviation of 400 milligals. One
milligal, according to Daly, would amount to about 10
meters of granite (97:394), so that the total deflection of the
crust from gravitational balance here would amount to 4,000
meters of granite, or, roughly, three miles of granite, which,
in turn, would be the equivalent of an ice sheet about nine
miles thick. And the crust has borne this enormous strain,
apparently, for some millions of years. According to Daly,
the Nero Deep, near the island of Guam, has deviations from
gravitational balance of the same magnitude (97:291). Among
uncompensated features on the lands are the Harz Moun-
tains, in Germany (97:349), and the Himalayas, which stand
about 864 feet higher than they should (97:235). A particu-
larly interesting case is that of the island of Cyprus, of consid-
erable size, which stands about one kilometer, or 3,000 feet,
higher than it should, and yet shows no signs of subsiding.
Daly says:
From Mace's table of anomalies and from his map, it appears
that we have here a sector of the earth, measuring more than 225
kilometers in length and 100 kilometers in width, and bearing an un-
compensated load equal to one kilometer of granite, spread evenly
over the sector. . . . (97:212-13).
These facts would appear to argue a very considerable
strength of the crust to resist the pressure toward establish-
ment of gravitational, or isostatic, balance. However, in all
the cases so far mentioned it is true that the deviations have
174 EARTH'S SHIFTING CRUST
occurred in comparatively narrow areas. The Hawaiian
Islands, for example, represent a long, narrow segment of the
crust. Obviously the crust can support loads with small span
more easily than loads with a very great span. These devia-
tions, therefore, may not tell us much about the gravitational
status of the Antarctic icecap, which, of course, has an enor-
mous span, since it covers a whole continent. Since they are
insignificant quantitatively as compared with the possible
effect of the continental icecap of Antarctica, they will not,
of themselves, answer Einstein's question.
Of more importance are isostatic anomalies of broad span,
and these are, surprisingly, quite plentiful. Daly mentions
one along the Pacific coast. This is a negative anomaly—
a deficiency of mass. Daly explains that according to one
formula (the "International Formula"), it covers an area
2,100 miles long, and 360 to 660 miles wide; according to
another formula (the "Heiskanen"), it is reduced to one half
both in intensity and in extent (97*371). Taking the lesser es-
timate, the deficiency of mass over this large area still amounts
to the equivalent of a continuous ice sheet 1,000 to 1,200 feet
thick. So it appears that over this large span the crust can bear
that amount of negative weight (that is, of pressure from with-
in the earth) without giving way, at least for a short period of
time. In other parts of the United States there are positive
anomalies of the same magnitude, and these obtain over large
areas.
A far more extraordinary case is an enormous area of nega-
tive mass that covers part of India and most of the adjacent
Arabian Sea. The width of the negative area in India is 780
miles. Daly, after noting the challenge presented by this
fact to the whole theory of isostasy, goes on to say:
The situation becomes even more thought provoking when we
remember that Vening Meinesz found negative Hayford anomalies
all across the Arabian Sea, 2500 kilometers in width. Apparently,
therefore, negative anomalies here dominate over a total area much
greater than, for example, the huge glaciated tract of Fenno-Scandia
[Finland and Scandinavia]. And yet there is no evidence that the
THE SHAPE OF THE EARTH 175
lithosphere under India and the Arabian Sea is being upwarped.
The fact that Fenno-Scandia, though less (negatively) loaded than the
Arabian Sea-India region, is being upwarped, as if by isostatic adjust-
ment, emphasizes the need to examine the Asiatic field with particular
care. . . . (97-365)-
Let us remember that a negative load means simply pres-
sure from within the earth outwards, and positive load pres-
sure from the surface inward. In principle, they are the same
in so far as their evidence for the strength of the crust goes.
It seems that here the crust is quite able to bear a large load
over a great span without yielding. Daly points out that many
parts of India are distorted on the positive side; there is an
excess of matter over considerable areas, and he remarks:
. . . India, among all the extensive regions with relatively close
networks of plumb-bob and gravity stations, is being regarded by
some high authorities as departing so far from isostasy that one
should no longer recognize a principle of isostasy at all. . . . (97:224-
*5).
A particularly important aspect of these great deviations
from gravitational balance of the crust in India is that they
are not local distortions, not the result of local surface fea-
tures such as hills and valleys. These surface features may
well once, and quite recently, have been in good isostatic bal-
ance. The distortion lies deeper:
... In India practically all the gravity anomalies seem to have
no apparent relation to local conditions. Only one explanation
seems possible— that is, that they are due to a very deep seated gentle
undulation of the lower crustal layers underlying all the super-
ficial rocks; it is evidently a very uniform, broad sweeping feature
at a great depth, and must be uncompensated, since if it were
compensated it would cause no anomaly at the surface (97:241-42).
Forced to find some way of explaining how the crust could
bear such loads (positive and negative) in India and still yield
easily to isostatic adjustment in other areas, Daly suggests
that the strength of the crust in India might be explained by
a recent lateral compression of the whole peninsula, which,
176 EARTH'S SHIFTING CRUST
he says, is evidenced by the folding there of the young sedi-
mentary rocks (97:391-92).
Daly does not suggest a possible cause for this lateral com-
pression of the whole peninsula; such a compression, part of
the process of mountain building, he has already character-
ized as "utterly mysterious." But it must be clear that it is
precisely the type of distortion that might be expected to re-
sult from a displacement of the earth's crust. Such a move-
ment could very well account both for the depression of
lower India and for the uncompensated elevation of the
Himalayas. It can be said, moreover, that no displacement of
the crust could possibly take place without creating, at some
points on the earth, precisely such deep-lying gentle undula-
tions of the crust.
But still another point may be urged in support of this
solution of the problem. We shall see, later on, that the last
movement of the crust appears to have been approximately
along the goth meridian, with North America moving south-
ward from the pole. This movement would have subjected
India to maximum displacement and to maximum compres-
sion. In this last movement India would have been moved
across the equator and northward toward the pole, to its
present latitude.
Daly's suggestion that compression may increase the tensile
strength of the crust opens up most interesting possibilities.
We may find here, in connection with the theory of crust dis-
placement, a solution to very puzzling problems of isostatic
theory. The crust of the earth shows enormous differences
from place to place in its degree of isostatic adjustment and
in its sensitivity to the addition or removal of loads. Apply-
ing Daly's suggestion, we may infer that the differences may
owe their origin to recent displacements of the crust. Areas
recently moved poleward, having undergone compression
and still retaining compression, would, according to Daly's
suggestion, have greater strength to sustain the distortions;
areas recently displaced equatorward, having undergone
extension, or stretching, would have less strength to resist
THE SHAPE OF THE EARTH 177
gravitational adjustment, and, moreover, the widespread
fracturing accompanying the movement would facilitate ad-
justment.
This suggestion of Daly's also has great significance for the
understanding of the absence of much volcanism in the polar
regions. It has been observed that these regions are relatively
quiet, with respect to volcanoes. There is only one volcano in
the whole continent of Antarctica, so far as we know. What
can be the reason for this? It may be thought that this may
result from the polar cold, but this cannot be true. The influ-
ence of surface temperatures penetrates only a short distance
into the crust; volcanoes originate from greater depths. The
solution may be found in the fact that, according to our
theory, both the present polar areas are areas that were
moved poleward in the last movement of the crust, and were
therefore compressed. Consequently, the crust in those areas
was less fractured and now has greater strength to prevent
volcanic action. This increased strength may also have the
effect of adding to the ability of the crust to sustain the in-
creasing weight of the icecap, without giving way, thus tend-
ing to add to the uncompensated proportion of the icecap. In
addition, Antarctica may well show isostatic distortions of
the crust itself, equivalent to the positive anomalies in India.
The importance of finding a reasonable solution for the
profound contradictions in the theory of isostasy has been
emphasized by several recent writers. Professor Bain, of Am-
herst, writes:
Isostatic adjustment exists only in imagination. I present the ex-
istence of peneplains in witness thereof. Establishment of the
Rocky Mountain peneplain or the Old Flat Top Peneplain of the
western states requires erosion of at least 10,000 feet of the rock over
the main arch of the Front Range. The rivers wore the land down
slowly to grade equilibrium without observable rise of the unloaded
region or subsidence of the loaded region throwing all gravity out
of equilibrium. Then in the brief interval of a small part of a
geological epoch the land surface rose to re-establish near gravity
equilibrium. . . . (19).
178 EARTH'S SHIFTING CRUST
Now, as I understand Professor Bain's statement, his point
is that in numerous instances erosion has worn away moun-
tain ranges, leaving flat plains (peneplains), and in the in-
stance he cites it seems that during the prolonged period
when the erosion was taking place (erosion that resulted in
removal of no less than 10,000 feet of rock from one area, and
the deposition of the resulting sediments in another), the
crust did not respond by rising in the first area and sinking
in the second. Gravitational balance was thus sadly set askew,
and remained so for a long time. Then, relatively suddenly,
equilibrium was re-established. How do we explain this?
I think it is necessary to take into consideration the fact
that just as compression will be at a maximum along the
meridian of displacement of the crust in the poleward direc-
tion, extension or stretching will likewise be at a maximum
along the same meridian in the equatorward direction. But,
in both cases, areas removed from this meridian will be dis-
placed proportionately less, and large areas will undergo very
little or no displacement, and consequently very little or no
compression or extension. Since, as we saw in the last chapter,
successive movements of the crust may oscillate along merid-
ians placed close together, it follows that, for long periods,
compression may be sustained in particular areas and isostatic
adjustment impeded in those areas. Eventually, a movement
of the crust in a different direction will permit the delayed
adjustment to take place.
In this way, too, we may explain the data upon which Dr.
Jeffreys based his conclusion that isostasy is an exceptional
condition of the earth's surface, which is re-established only
at long intervals. The theory presented in this book offers a
solution for the cause of the geological revolutions which,
he supposed, shattered the crust at long intervals, bringing
about the formation of mountains, and permitting the re-
establishment of crustal balance.
With regard to the vast negative or positive distortions of
isostasy, the displacement theory has a solution to offer. Let
us suppose a movement of the crust causing widespread slight
THE SHAPE OF THE EARTH 179
distortion of the earth from its equilibrium shape, distortion
such as now prevails across parts of India and all of the
Arabian Sea. It is essential to realize that the long persistence
of such anomalies, and the apparent lack of any tendency to
adjustment, may have no relationship to the strength of the
crust. It may be due, quite simply, to the fact that the matter
in the sublayer (the asthenosphere) is too viscous to flow
rapidly, and that when it has to flow such great distances, and
in such great volume as would be required to compensate the
sweeping undulations of the geoid caused by a movement of
the crust, great periods of time are required, periods so long
that our instruments have not been able to detect the progress
of isostatic adjustment.
The advantage of the theory of crust displacements is that
it can reconcile the data supporting the conviction of geolo-
gists that the crust must be too weak to support major loads
out of adjustment over great spans of territory, with the ob-
served fact that in some cases it appears to do so. Further-
more, we may, with this theory, grant the crust enough
strength under certain conditions (of compression) to sup-
port heavy loads of narrow span, such as the Hawaiian
Islands, and still understand its extreme weakness in areas of
extension, where it appears to adjust easily to rather minor
loads.
Einstein, in the Foreword, referred to the possible centrif-
ugal effects of these distortions within the crust. The follow-
ing principles apply:
a. A positive load on the crust, like the icecap, will exert a
centrifugal effect equatorward; correspondingly, the
effects of negative loads must be poleward.
b. The effects of positive loads on one side of the equator
will be opposed to the effects of positive loads on the
other side of the equator; equal positive loads in equal
longitudes and latitudes will cancel each other across the
equator, and the same is true of negative loads.
i8o EARTH'S SHIFTING CRUST
c. Despite the fact that such loads may cancel each other
wholly or in part, in so far as the transmission of a net
centrifugal momentum to the crust in any given direc-
tion is concerned, nevertheless their opposition will in-
volve the creation of persisting stresses in the crust, and
these may be a cause of seismic activity.
d. Crustal distortions, unlike icecaps, are comparatively
permanent features; many may persist through one or
more displacements; their effect will change quantita-
tively according to their changes of latitude and longi-
tude.
e. At the termination of each crustal movement, the dis-
tortions of the rock structures of the crust should be
approximately balanced across the equator. In a period
of several thousand years following such a movement,
however, the process of isostatic adjustment, proceeding
faster in some areas than in others, may disturb this
balance and predispose the crust to a new displacement.
f. We may conclude, in answer to the question raised in
the Foreword, that while some of these distortions are
massive, they tend to be balanced across the equator,
and that the principal disturbing factor, from the
quantitative standpoint, must in all probability be the
rapidly growing continental icecap.
4. The Triaxial Shape of the Earth
We cannot leave the subject of the gravitational adjustment
of the earth's surface without mentioning the greatest dis-
tortion of all, the triaxial deformation of the earth. It is all
the more important to consider this question since here we
shall see, at one and the same time, a solution for one of the
greatest of geological conundrums, and one of the most
powerful arguments in support of the theory of displace-
ments of the earth's crust.
Not long ago, scientists became aware of the fact that there
THE SHAPE OF THE EARTH l8l
is a deviation in the shape of the earth from the idealized
form of a flattened, or oblate, spheroid. The increasingly
accurate measurements of geodesy have shown that the earth
has bumps and irregular lumps in various places, which seem
to correspond to a third axis running through the earth. As
a result of this, scientists now consider that the true shape
of the earth is that of a "triaxial ellipsoid."
An axis, of course, is not a material thing. It is only a line
that somebody imagines running through a sphere to give a
dimension to that sphere in that direction. Three axes of the
earth mean one through the poles, on which the earth rotates
(the axis of rotation); one through the equator, called the
equatorial axis, twenty-six miles longer than the polar axis;
and now a third axis, roughly through the equator, at an
angle to the other equatorial axis.
The result of having two axes of different lengths running
through the equator is, of course, that the equator itself is a
little flattened; it is oval, rather than truly circular. The flat-
tening is very slight. According to Daly, one axis through the
equator is 2,300 feet longer than the other (97:32); Jeffreys,
according to Daly, prefers half that figure. Daly finds that the
longer diameter through the equator (the major axis) runs
from the Atlantic Ocean, at 25° W. Long., to the Pacific, at
155° E. Long., and the shorter diameter (or minor axis) runs
from the western United States, at 115° W. Long., to the
Indian Ocean, at 65° E. Long. (97:32). Just as the actual
amount of the flattening of the equator is uncertain, so are
the precise situations of the major and minor equatorial
axes. More recently, determinations by the United States
Coast Geodetic Survey have suggested a slightly different
position for one of these axes. Moreover, the third axis ap-
parently does not run precisely through the equator. The
result is that the earth's shape is distorted by protuberances
of various sizes and shapes. If we take Jeffreys's estimate of
their magnitude, we see that they amount to the equivalent
of about 2,000 feet of rock, or over a mile of ice, and of
182 EARTH'S SHIFTING CRUST
course the anomalies have enormous spans, on the order of
thousands of miles.
Despite their vastly greater magnitude, these triaxial pro-
tuberances have one thing in common with those in India.
Just as Daly observed that the Indian anomalies must result
from sweeping undulations of the geoid at some depth in the
crust, underlying all the surface features, so do the triaxial
protuberances indicate distortion in depth rather than at the
surface. In India the surface features would be in fairly
good isostatic adjustment if the deep-seated undulations were
disregarded, while the geodesist Heiskanen, according to
Daly, found that if he disregarded the triaxial protuberances
—if he regarded the triaxial ellipsoid as the natural shape of
the earth— all his anomalies were reduced to one half, both
in extent and in intensity (97:368).
It does not seem reasonable simply to disregard distortions
of the shape of the earth of this magnitude, unless we have an
explanation of them that is convincing. Daly provided an ex-
planation, but for a number of reasons it seems to me unsatis-
factory.
It was plain to him that the strength of the crust could
not possibly support such enormous distortions over such
spans. Therefore he made one or two alternative suggestions,
advancing them as possibilities only. He suggested, first, that
assuming an original molten condition of the earth, it is
possible that the material in the liquid melt was not of uni-
form density on opposite sides of the earth, and that there-
fore when the mesosphere (the inner solid shell underlying
the asthenosphere) solidified, it was heavier on one side than
on the other— that is, lopsided— and the resulting unevenness
of gravity at the surface influenced the equilibrium, that is,
the elevation from place to place, of the surface layers. This
is an ingenious suggestion, but it requires the assumption of
the cooling of the earth, which is itself doubtful. Thus this
particular explanation rests upon speculation, and upon
speculation that is not well supported.
The same is true of Professor Daly's second suggestion. He
THE SHAPE OF THE EARTH 183
supposes that the lopsidedness of the internal shell may have
resulted from the separation of the moon from the earth, at
which time the bed of the Pacific may have been created.
The arguments that once supported this theory of the origin
of the moon have, in recent years, been gradually whittled
away, until little remains of them. This, then, is also a haz-
ardous speculation.
Professor Daly's fertile mind has produced a third sugges-
tion. He feels that perhaps the triaxiality may have resulted
from the effects of continental drift, which he felt himself
compelled to support because there was no other way to ex-
plain the innumerable facts of paleontology and geology,
many of which have been already cited in this book. We have
seen, however, that continental drift will not do.
It seems that all the arguments that Professor Daly uses to
support his suggestion that the triaxial protuberances are not
supported by the crust, but from below the crust, fail to stand
examination. They are supported by no convincing mass of
evidence. There is obviously a sort of desperate urgency
about them. A strong need impels him to hoist them up. The
nature of this need is perfectly clear.
The need is to save the theory of isostasy. It is to smooth
the path in front of a theory that has a lot of useful applica-
tions and has a great deal to be said for it. The theory is
threatened by the unexplained anomalies referred to above;
it is still more threatened by these massive distortions of
the shape of the planet, the triaxial protuberances. They are
wholly and absolutely irreconcilable with the known prin-
ciples of physics, as opposed to speculations. Either the shape
of the earth is established by the balance of the force of grav-
ity and the centrifugal effect of the rotation, or it is not. The
geoid, so established, is distorted, and it proves impossible
to explain the distortion either by the resistance of the crust
to the aforementioned forces or by the (undemonstrated) lop-
sidedness of the internal shell.
But displacements of the earth's crust may explain the
matter, and in the simplest possible fashion.
184 EARTH'S SHIFTING CRUST
We have seen that areas displaced poleward in a movement
of the crust will be elevated relatively to sea level. Two areas
will be displaced poleward at the same time, one to each pole,
and both will be elevated somewhat with reference to the
equilibrium surface. The distance through the earth between
these points will be increased slightly. At the same time, two
other areas will be displaced equatorward. They will subside,
and the diameter through the earth between them will be
shortened to some extent. These areas will be centered on
the meridian of the movement of the crust. At 90 degrees'
remove on each side from this meridian, there will be no
movement; here are the so-called "pivot areas*' that do not
change their latitude. They will therefore not change their
elevation: a diameter through the earth between them will
be unchanged.
As the consequence of this, we see that in one direction
the diameter of the earth through the equator is shortened;
in the other direction through the equator it is not. The re-
sult must inevitably be the ellipticity, or ovalarity, of the
equator.
The consequences of the displacement do not end here. As
we have stated from time to time, much complicated folding
and faulting of the crust, much shifting of matter below the
crust, would be inevitable or likely, and these would have
effects at the surface, including basining and doming. Hence,
some of the protuberances now being discovered may have
nothing to do with the triaxial distortions, and may simply
be confused with them.
Now, it is clear that this explanation of the triaxiality re-
quires neither complicated and hazardous speculations about
the earth's interior nor an incredible strength in the earth's
crust. The protuberances remain because the matter below
the crust is too highly viscous to flow the great distances and
in the great volume that would be required to re-establish
the normal shape of the earth: that is, it is too viscous to have
been able to do so in the very short period that has elapsed
since the last movement of the crust. But no doubt the read-
THE SHAPE OF THE EARTH 185
justment is proceeding slowly; no doubt the triaxial bumps
are now the reduced remnants of those that existed at the
end of the last movement of the crust.
If all anomalies in the crust cause centrifugal effects, then
these vast triaxial protuberances must do so. These must, as
I have pointed out, be balanced across the equator, or have
been so at the termination of the last movement. Since then,
isostatic adjustment has probably been proceeding, and
therefore the balance of forces established when the crust
stopped moving may now no longer exist. The instability of
the crust may have been thereby increased, and the effects of
its instability may supplement the increasing thrust of the
growing, eccentric icecap. This suggests that the balance of
the crust in its present position may be only a "trigger bal-
ance."
5. The State of Matter Below the Crust
The theory presented in this book depends upon the rela-
tionship between three factors: the quantity of the momen-
tum transmitted to the crust by the icecap, the tensile
strength of the crust, and the degree of weakness prevailing
in the subcrustal layer, or asthenosphere. In Einstein's opin-
ion, the existence of sufficient weakness in the asthenosphere
to permit the displacement of the crust was the only doubtful
assumption of the theory. However, we find that one and the
same assumption is required for this theory, and for the
whole theory of isostasy. It is my opinion that the theories
stand or fall together.
In conceiving of the asthenosphere, we should not imagine
a layer of soft rock distinguished from the crust and from the
inner shells of the earth by sharp lines of demarcation. In-
stead, one grades off insensibly into another, and in all prob-
ability inequalities in thickness exist from place to place.
It is the general opinion of geophysicists that at a certain
depth in the crust increasing heat and pressure bring about a
i86 EARTH'S SHIFTING CRUST
diminution of the tensile strength and rigidity of the rock.
The decline of strength continues to the bottom of the crust.
Dr. Jeffreys remarks: ". . . At some depth ... it begins to
decrease and may be a tenth of that of surface rock at a depth
of 30 miles. . . ." (238:202).
At the bottom of the crust, perhaps about 36 miles be-
low the surface of the earth, an important change of state
apparently takes place. The heat reaches the melting point
of the rocks, and the rocks can no longer crystallize. Since the
strength of rocks depends mostly upon a structure of strong,
interlocking crystals, the change of state implies a disappear-
ance of strength. For this reason Professor Daly considers the
asthenosphere to be "essentially liquid/' ". . . For it is
hardly to be doubted that a rock layer, too hot to crystallize,
has only a minute strength, or no strength whatever" (97:399-
400).
Jeffreys is in agreement that the melting point of rock
should be reached about 36 miles down (238:140), judging
from the heat gradient.
If it were only a question of the crystalline or noncrystal-
line structure of the rock, we would readily conclude that
the asthenosphere could offer no serious resistance to the dis-
placement of the crust. The crust would be truly (to use Ein-
stein's term) a "floating crust."
But we must also take into account another quality of mat-
ter, which is viscosity. Materials possess varying degrees of
viscosity. Viscosity can make a liquid act like a solid. If, for
example, a high diver hits the surface of the water at a bad
angle he may kill himself, because the water, though liquid,
requires time to flow, and if the impact is too sudden there
is no flow and the liquid acts as a solid. Tar is an example
of a more viscous substance. Taffy candy is highly viscous,
and can be cut with scissors, and yet, given a certain amount
of time, it will flow like a liquid. The effect of pressure on
different substances is to increase their viscosity, to make
them stiffer. They will then resist sudden shocks better, but
will flow like liquids if subjected to steady pressure for a con-
THE SHAPE OF THE EARTH 187
siderable period of time. The layer immediately under the
earth's crust is subjected to high pressure, and therefore,
although it is liquid, it may be stiff. The stiffness can be ex-
pected to be least immediately under the crust, and to in-
crease with increasing depth.
However, it cannot be assumed that the viscosity imme-
diately under the crust is very great. Bridgman has pointed
out that it depends to a great extent on the particular chem-
ical composition of the rocks, which necessarily is uncertain
(50). Moreover, though pressure increases viscosity, heat
diminishes it, again differently for different chemical sub-
stances. It is difficult to estimate the net effect of the opera-
tion of these opposite influences at any point under the crust.
Daly presents evidence that the viscosity of the astheno-
sphere must be very low. He cites, first, evidence from the
edges of the area recently occupied by the Scandinavian ice-
cap. According to isostatic principles, viscous rock must have
flowed out from under the section of the crust loaded by the
icecap. If the rock was very stiff, Daly argues, it would not
have flowed very far, but would have upheaved the crust
around the fringes of the ice sheet. Evidences of such up-
heaval should be observable, but there are none. He thinks
that there should have been an upheaval of the Lithuanian
plain, but none occurred. Hence his conclusion is that the
asthenosphere must have low viscosity: ". . . And there is
no apparent necessity for excluding the possibility of effec-
tively zero strength*' (97:389).
The meaning of this geological evidence appears to be
that the asthenosphere must be a true liquid in terms of
pressure applied over periods of the length required for the
growth of the Scandinavian icecap, which would be the same
length of time that we suppose would be involved in a dis-
placement of the crust.
As a second line of evidence for a weak sublayer, Daly
points out (as already mentioned) that in mountain making
the crust is folded to its full depth, that horizontal sliding has
to occur to permit this folding, and that horizontal sliding
188 EARTH'S SHIFTING CRUST
would be impossible if the asthenosphere had any consider-
able strength. In his opinion mountain formation requires
the existence of a zone of easy shear.
Thirdly, Daly urges the importance of the general body
of evidence of igneous geology:
. . . The existence of a liquid or approximately liquid astheno-
sphere is strongly suggested by the countless facts of igneous geology.
The hypothesis that the lithosphere is crystalline, a few scores of
kilometers in maximum thickness, and everywhere underlain by a
hot vitreous substratum provides what appears to be the best work-
ing theory of the chemical nature of magmas and their modes of
eruption. ... In general, no petro-genetic theory that does not rec-
ognize a specific world-encircling asthenosphere of this kind has
been found to explain so many facts of the field. . . . (97:399-400).
Among specific evidences that point, in Daly's opinion, to a
really liquid asthenosphere are the plateau basalts, which,
as we have seen, were formed by immense floods of liquid
magma that engulfed hundreds of thousands of square miles
of the surface at one time.
Jeffreys opposes Daly's view of the asthenosphere, and ar-
gues for continuation of considerable strength to a depth of
several hundred miles. Daly notes his argument, and an-
swers it.
Jeffreys's argument is based on the fact that an analysis of
earthquake waves shows that some earthquakes originate at
depths up to 420 miles below the surface. Presumably, they
can originate only as the result of fracture in a solid substance,
which necessarily would have some strength. Daly remarks:
For example, Jeffreys deduces, from the reality of deep-focus shocks,
a strength of about 1000 kilograms per square centimeter for the
material reaching down to the 7oo-kilometer level at least. This
is about the strength of good granite in the testing machine.
To reconcile that conclusion with the demonstrated degree of
isostatic equilibrium, Jeffreys suggests that isostasy is a highly ex-
ceptional condition of the earth. He assumes the condition to have
been established during major orogenic disturbances, and preserved
for only a relatively short time after each paroxysm of mountain-
making (97:400-01).
It is not easy to reconcile Jeffreys's views here with those
: his I have quoted above regarding the decline of strength
: rock with increasing pressure in the crust. It is evident
iat if Jeffreys is right, the theory of isostasy is reduced to
shambles. But Daly presents a counterargument to show
iat he is not right. He suggests that at great depths the vis-
>sity would be so high that a comparatively sudden ac-
imulation of strain from some cause could fracture the rock
if it were a solid. Laboratory experiments conducted by
ridgman have shown that solids subjected to pressures so
•eat as to make them flow behaved in very peculiar fashion,
hey would flow, but the flow would, at times, be interrupted
f fracture and slip. Daly also quotes Gutenberg to the effect
iat ". . . Whereas at normal depths the accumulation of
rain is made possible by the strength of the rocks, at the
•eater depths the high coefficient of viscosity is sufficient,
id no conclusion as to strength can be drawn" (97:403).
hus the counterargument is a strong one. All that is neces-
ry, in fact, both for the theory of isostasy and for the theory
: displacements of the crust is a thin layer of extreme weak-
*ss at the top of the asthenosphere, where the viscosity
ould be much less than at the greater depths.
According to Daly, Jeffreys adopted his view because he
>uld see no reason for the development of sudden stresses
the greater depths. Daly argues that this cannot settle the
atter; perhaps we shall eventually discover a sufficient
Luse. Daly also says, when speaking of the earth's triaxiality,
iat it means "stress at depths of thousands of kilometers"
7:404). Putting two and two together, I would suggest that
ie deep-focus earthquakes result from the triaxiality, and
iat the stresses develop suddenly enough to exceed the lim-
5 of the viscosity at that depth and cause fracture, because
te triaxial bulges are not permanent features of the planet,
it recent deformations, which must set up strains at con-
ierable depths.
Archibald Geikie describes experiments done a long time
190 EARTH'S SHIFTING CRUST
ago, which are still suggestive of the probable behavior of
material in the asthenosphere:
The ingenious experiments of M. Tresca on the flow of solids
have thrown considerable light on the internal deformations of rock-
masses. He has proved that, even at ordinary atmospheric tempera-
tures, solid resisting bodies like lead, cast iron, and ice may be so
compressed as to undergo an internal motion of their parts, closely
analogous to that of fluids. Thus a solid jet of lead has been pro-
duced, by placing a piece of the metal between the jaws of a power-
ful compressing machine. Iron, in like manner, has been forced to
flow in the solid state into cavities and take their shape. On cutting
sections of the metal so compressed, their particles of crystals are
found to have arranged themselves in lines of flow which follow
the contours of the space into which they have been squeezed. . . .
(170:316).
It seems altogether unlikely that material under the pres-
sures prevailing at the bottom of the crust, and at very high
temperatures, could resist the shearing movement of the crust
over it. Let us remember that in a displacement of the crust
very little material, comparatively speaking, would actually
have to flow. The crust would simply start to slip over the
asthenosphere. The action would be one of gliding, the most
economical form of motion, though, as already explained,
the downward protuberances of continents and mountain
chains might act to slow down the movement.
To conclude, then, the asthenosphere could have consid-
erable viscosity, even at the top, and yet offer no definite
obstacle to the displacement of the crust. Once the crust
started to move, the braking influence of the viscosity would
steadily decline, for with the increasing distance of the cen-
ter of mass of the icecap from the axis, the centrifugal effect
would be multiplied (Chapter XII). No friction between the
two layers could suffice to absorb this ever increasing thrust.
It would have to continue until the motive force was re-
moved by the melting of the icecap in the warmer latitudes.
And, in the meantime, as Frankland has suggested, the fric-
tion would have been productive of heat that might have
further facilitated the movement.
THE SHAPE OF THE EARTH 1Q1
I have not referred to another important aspect of the be-
havior of materials under pressure, one that may have its
importance. If the viscosity of matter increases with pressure,
so does plasticity. Solids become more and more plastic under
pressure. At the bottom of the crust matter is under enor-
mous pressure. That means that very little force may be re-
quired to overcome its rigidity. It also means that when a
critical point is reached, the material may deform suddenly.
It does not give way at a speed proportional to the pressure
applied, as khthe case of a viscous liquid, but at a speed that
has no relationship to the applied force. Bridgman has
pointed out that the exact degree of plasticity at the bottom
of the crust, like that of the viscosity, cannot be determined
because of our ignorance of the chemical composition of the
materials.
This question of plastic deformation raises an interesting
possibility. What if, at a certain point in the displacement,
viscous deformation gives way to plastic deformation? Sup-
pose the movement starts slowly as a gliding over a viscous
surface. Suppose it gains enough speed so that, at the inter-
face between the crust and the underlying plastic layer, a
plastic type of yielding occurs. The interactions here would
be complex, but the possibility looms that at times the dis-
placement of the crust could take place with considerable
speed.
I have mentioned that the gliding motion of the crust
might be impeded at times by the downward projections of
its undersurface. However, if there is one situation in which
plastic deformation might be considered probable, it is one
in which these downward projections— for example, the un-
derbody of a continent— were displaced against upward pro-
jections of the asthenosphere under the ocean basins. Here
considerable pressures would arise, and various circumstances
might concentrate these pressures in narrow regions and in-
tensify them; the pressures might thus reach the critical
point of plastic deformation, and result in the abrupt shear-
ing off of larger or smaller segments of the downward pro-
192 EARTH'S SHIFTING CRUST
jections of the crust—the roots of continents and mountain
ranges. This would result in comparatively sudden changes
at the surface, at least in areas being moved equatorward and
thus stretched and weakened. It would also facilitate the
process of planing off and shaping the continental sides as
suggested in the last chapter.1
i Newspaper reports of observations now being made in Antarctica, as part of
the scientific program of the present International Geophysical Year, indicate
a depth for the ice sheet at the South Pole of about 8,000 feet. This suggests
that Campbell and I may have considerably underestimated the total mass
and weight of the icecap. At the same time, the reports suggest very low pre-
vailing temperatures, and therefore high rigidity, for the ice, at some depth
below the surface. (See p. 170.)
VII : NORTH AMERICA AT THE POLE
In the preceding chapters much evidence has been presented
to support the contention that the earth's crust has often
been displaced. Perhaps the reader will feel that the general
evidence is sufficient. It remains, nonetheless, to show be-
yond a reasonable doubt that such a movement actually did
occur in one specific instance. I have already suggested that
the last movement may have been the immediate cause of
the end of the last ice age in North America and in Europe.
In this chapter I will review the evidence for this. At the
same time, I will try to show why the circumstances of
the displacement themselves indicate and, in fact, require the
further conclusion that the icecap in North America must
itself have been the agent of the displacement.
/. The Polar Icecap
Several independent lines of evidence, each individually ex-
tremely impressive, unite to suggest that the Hudson Bay
region lay at the North Pole during the so-called Wisconsin
glaciation.
The first line of evidence is based on the shape, and on
the peculiar geographical position, of the last North Amer-
ican icecap. Kelly and Dachille point out that the area occu-
pied by the ice was similar both in shape and in size to the
present Arctic Circle (248:39). Many geologists have re-
marked on the unnatural location of the icecap. It occupied
the northeastern rather than the northern half of the con-
tinent. Some of the northern islands in the Arctic Ocean,
and northern Greenland, were left unglaciated (87:28, note).
Alaska and the Yukon had mountain glaciers but no con-
tinuous ice sheet. Then, the ice is known to have been thicker
194 EARTH'S SHIFTING CRUST
and to have extended farther south on the low central plains
of the Mississippi Valley than it did on the high mountain
areas in the same latitudes farther west. But according to ac-
cepted ideas about glaciation, if the ice age was the result of
a general lowering of world temperatures, the ice should
have formed first in the mountain areas, and it should have
extended farther south on them than in the low plains.
There has been no explanation of this, which may have been
one of the problems that led Daly to remark that "The Pleis-
tocene history of North America holds ten major mysteries
for every one that has already been solved" (93:111).
The assumption that the Hudson Bay region then lay at
the pole would make the facts easy to explain, for in this case
the western highlands would lie to the south of the plains
region, and one would therefore expect thicker ice on the
plains lying nearer the pole. Absence of continuous glacia-
tion in Alaska and in the Arctic islands would be easily ex-
plained. Furthermore, the fact that the European ice sheet
was thinner than the North American and did not extend
so far south would be understandable. The relationship be-
tween the North American and contemporary European
glaciations will be discussed further below.
A second line of evidence for the position of North Amer-
ica at the pole consists of the new data regarding recent
climatic change in Antarctica, already discussed (Chapter II).
A movement of the crust that would move North America
southward about 2,000 miles would also necessarily move
Antarctica that much nearer the South Pole (see globe).
Therefore, a displacement of the crust accounts both for the
deglaciation of North America and for the expansion of the
icecap in Antarctica, and it accounts for the two events being
simultaneous. No other hypothesis so far suggested can ac-
count for climatic revolutions in opposite directions on the
two continents. No assumption of ice ages resulting from a
simultaneous world-wide reduction of temperature will fit
the facts. In a personal interview, I once asked Einstein if
NORTH AMERICA AT THE POLE
he could see any logical alternative to crust displacement
as the explanation of these facts. He replied that he was per-
suaded of the soundness of the method of crust radioelement
dating developed by Professor Urry, and that he saw no other
reasonable explanation of the evidence (see page 364). A third
line of evidence is that presented by Dr. Pauly, already dis-
cussed (Chapter III).
A fourth line of argument is developed by Lawrence Dil-
lon, who shows, first, that the essential condition governing
the growth of ice sheets seems to be not the average year-
around temperature, nor the amount of annual precipitation,
but the mean summer temperature (114:167). He points out
that no ice sheets form at the present time in areas with mean
summer temperatures of 45° F. or higher, and suggests that
they probably didn't in the past. He cites, as a good illus-
tration of this principle, the northeastern section of Siberia,
which is unglaciated despite the fact that it is the "cold pole"
of the world, and although it has a higher annual precipita-
tion than Greenland or Antarctica. But the summer tempera-
ture is high, and this he thinks is the controlling factor.
Dillon points out, next, that the existence of the Wisconsin
glacier would have demanded a decrease of 25° C. in average
summer temperatures as they exist now (114:167). But he
notes that according to Antevs the average temperature de-
crease in late Pleistocene time along the iO5th meridian in
southern Colorado and northern New Mexico as compared
with the present was only 10° F., while (according to Meyer)
the average temperatures during the glacial period in the
equatorial Andes were only 5° or 6° F. lower than at pres-
ent (114).
Thus Dillon shows that there was no uniform decrease of
summer temperatures during the glacial period. No world-
wide factor, such as variations in solar radiation, reduced the
temperature. The range of summer temperatures would be
understandable if the ice sheet were a polar icecap, however,
and the range appears to require that assumption.
196 EARTH'S SHIFTING CRUST
... On the other hand, the only apparent alternate hypothesis—
that of a uniform depression of the mean temperature of say 10° F.
would suggest a July mean of 60° F. for the ice sheet's lower boundary,
which is similar to that of present-day England, or northern Ger-
many, or the State of Maine, but with somewhat colder winters.
Since no glaciers or permanent snow fields are known to exist today
under such mild climates, it seems scarcely likely that they could have
done so in former times (114:168).
Dillon does not explicitly suggest a movement of the crust,
but he leaves no alternative.
A fifth line of argument may be based on some evidence
used by Wegener to support his theory of drifting conti-
nents. He quoted the glaciologist Penck as saying that the
Pleistocene snowline lay about 1,500 to 1,800 feet lower in
Tasmania than in New Zealand, and added, "This is very diffi-
cult to understand because of the present nearly equal
latitudes of the two localities" (450: 1 1 1). Wegener, of course,
explained the matter by his theory of continental drift. If,
however, his theory is rejected, crust displacement may pro-
vide a solution, for if the Hudson Bay region was then lo-
cated at the North Pole, as we suppose, Tasmania would
have been a good many degrees nearer the South Pole than
New Zealand, as a glance at the globe will make plain. An-
other bit of evidence that fits in here is the apparent retreat
of glaciers in South Australia about 10,000 years ago (16).
A sixth line of argument may be based on the evidence for
world-wide volcanism at the end of the Wisconsin glacia-
tion. Extensive volcanic activity is an inevitable corollary
of a general movement of the earth's crust. I shall present
the argument that the volcanism incident to the movement
accounts for the numerous oscillations of the Wisconsin ice
sheet, and for the following "Climatic Optimum."
A seventh line of evidence is provided by the mass of data
relating to changes in sea level at the end of the ice age. I
shall attempt to show that these changes cannot be explained
by the melting of the northern icecaps, though they may be
explained by a displacement of the crust, on the basis of
principles already discussed.
NORTH AMERICA AT THE POLE 1Q7
An eighth line of evidence is presented by the story of the
extinctions of many kinds of animals at the end of the ice
age, and this is so important that it will require a chapter by
itself (Chapter VIII). Much additional evidence based on ma-
rine and land sediments will also be presented later (Chap-
ter IX).
2. The Displacement Caused by the Ice Sheet
It may be argued that convincing evidence of a displacement
of the crust by no means requires the further conclusion that
the movement at the end of the ice age was the result of the
centrifugal effects of the North American icecap. A dozen
other possibilities may be thought to exist. Several of them
may be worth considering. Why, then, must we jump to the
conclusion that the event was related causally to the icecap?
There have been several suggestions to account for shifts
of the crust by other agencies than icecaps. What is the com-
mon element of these suggestions? It can easily be pointed
out. All of them involve long periods of time. Gold's sug-
gestion involves periods of the order of a million years.
Bain's involves periods of a great many million years be-
tween movements. Ma's involves long periods between
movements, terminated by cataclysms. Eddington's type of
displacement, if it could be made to work at all, would neces-
sarily be very slow. Besides their common inability to explain
the velocity of events revealed by the new methods of radio-
element dating, the suggestions are unsatisfactory also because
they are vague as regards the mechanism of displacement.
They can be grounded neither upon detailed observations
nor upon mathematical calculations. The mechanism devel-
oped by Campbell, on the other hand, is quite definite and
precise (although it, too, necessarily must involve assump-
tions). Of special importance is the fact that Campbell's
mechanism is capable of being checked against geological
observations in some detail.
198 EARTH'S SHIFTING CRUST
To begin with, it is clear that a massive centrifugal effect
must have been created by the Wisconsin ice sheet, if the
considerations presented in Chapter VI are sound. Radioele-
ment dating has shown that the ice sheet developed in a very
short time. A high degree of isostatic compensation of the
icecap is therefore unlikely, even if isostatic compensation
could really eliminate the effect.
It is significant that the Wisconsin ice sheet was asymmet-
rical in its distribution about the center from which it spread.
If we assume that the ice center from which the icecap
radiated coincided at that time with the pole, then this
asymmetrical distribution must have resulted in a centrifu-
gal effect. Furthermore, it appears that the great bulk of the
ice lay to the south of the ice center, and so therefore the
direction of the resulting centrifugal thrust would have been
southward, and the result would have been to shift the Hud-
son Bay region due south from the pole toward its present
latitude. This is indeed in remarkable agreement with the
theory. The facts are reported by W. F. Tanner, writing in
Science, under the title "The North-South Asymmetry of the
Pleistocene Ice Sheet" (414).
There are some comparisons between this North American
icecap and the present icecap in Antarctica that are worth
making. The North American icecap is thought to have cov-
ered about 4,000,000 square miles, as compared with the
nearly 6,000,000 square miles of the present Antarctic cap.
It may be asked, Why should the smaller North American
icecap have started a slide of the earth's crust, when this
larger one in Antarctica has not? The answer to this appears
to lie in the different degrees of eccentricity, or asymmetry,
of the two icecaps. In Antarctica, the pole is fairly near
the center of the continent, so that the real asymmetry of the
icecap is not at first glance apparent. In North America the
presumed pole in Hudson Bay or perhaps in western Quebec
was on the eastern side of the continent, quite near the sea.
In this situation, the icecap was more eccentric. Its center
of gravity was in all probability much farther from the pole
NORTH AMERICA AT THE POLE
than is the case in Antarctica, and the centrifugal effect ac-
cordingly would have been much greater in proportion to
the quantity of ice.
If the pole was situated in the Hudson Bay region, the
closeness of the sea would have been a factor aiding the rapid
growth of the icecap, and giving less time for possible
isostatic adjustment.
An additional observation worth making, perhaps, is that
if this vast ice sheet had developed so rapidly at the present
latitude of Hudson Bay, the centrifugal effect would have
been colossal. If the centrifugal effect of the Antarctic icecap,
with its center of gravity 345 miles from the pole, is sufficient
to produce a bursting stress almost equal to the estimated
tensile strengths of the crust, the smaller North American ice-
cap, with its center of gravity about 2,500 miles from the
pole, would have produced a bursting stress many times
greater than the crustal strength. Why this must be so, the
reader may see by referring to Figure XII (p. 343). On this
plate, the second parallelogram represents the centrifugal
effect of the present Antarctic icecap on the assumption that
the icecap could be displaced, without melting, as far as the
45th parallel of latitude. It is evident that at the 45th parallel
the centrifugal effect would be approximately six times
greater than the effect produced by the icecap with its center
of mass where it is now, about 345 miles from the pole. The
bursting stress would be increased in proportion, being al-
ways 500 times the centrifugal effect (Chapter XI). It seems
unreasonable to suppose that at the end of the ice age the
crust could have withstood a stress six times greater than
our present estimate of its strength.
The reader is free to conclude from the foregoing, either
that the North American icecap must have been a polar ice-
cap (because it could never have developed to its full size at
the present low latitude of the glaciated region without mov-
ing the crust) or that the movement of the crust from any
such agency is impossible. But, as we have seen (Chapter VI),
goo EARTH'S SHIFTING CRUST
he would have trouble in finding a reasonable basis for the
latter conclusion.
We can therefore conclude that, on the whole, the North
American icecap is a good candidate for the position of prime
mover in the last displacement of the crust. The argument
will be strengthened when we consider, below, its detailed
history, and the implications of the extraordinary tempo of
its development and of its subsequent decay. The essential
argument in favor of icecaps is the time factor, for the rate
of their accumulation and of their melting is obviously many
times faster than that of any other process creating unbalance
in the distribution of materials on the earth's surface.
Horberg has recently collected and studied, as already
mentioned, the radiocarbon dates bearing on the history of
the Wisconsin ice sheet. According to him, the following is
its short and violent history (222:281):
a. The first known advance of the icecap— its first ap-
pearance in Ohio— is dated at merely 25,100 years ago. This
is called the "Farmdale Advance." It was formerly thought
to have occurred as much as 100,000 or even 150,000 years
ago. This date, then, cuts the time for the later history of
the ice sheet by about three quarters. Six different radiocar-
bon dates, all of the Farmdale Advance, show that the ex-
pansion continued until at least 22,900 years ago, or for
about 3,000 years. Then there was an unexplained interval
of warm climate (which I will explain later on), called the
"Farmdale-Iowan Interstadial." This warm period lasted
about 1,500 years, during which the ice withdrew a certain
distance.
b. Following the recession, a new advance of the icecap
occurred. This is referred to as the "lowan Advance." It
began about 21,400 years ago, lasted about 700 years, and
was interrupted by a new recession about 20,700 years ago.
c. This second recession, after less than a thousand years,
was succeeded by an extremely massive advance during the
period from 19,980 to 18,050 years ago. These dates must
not be taken as absolutely exact; there is always a small mar-
NORTH AMERICA AT THE POLE 2O1
gin of error. This new expansion, called the "Tazewell Ad-
vance/' apparently carried the Wisconsin icecap to its maxi-
mum extension and greatest volume.
d. The Tazewell Advance was interrupted by a prolonged
period of warmth and recession called the "Brady Interval"
or "Brady Interstadial." This lasted between three and four
thousand years. It began before 16,720 years ago, and ended
sometime after 14,042 years ago. The ice retreated a long
way.
e. A fourth advance of the ice sheet beginning about
13,600 years ago, and continuing to about 12,120 years ago
(called the "Gary Advance"), was followed by the "Two
Creeks Interstadial," an interval of warmth and recession,
about 11,404 years ago.
f. A fifth advance of the ice, referred to as the "Mankato
Advance," appears to have taken place between 10,856 and
8,200 years ago. The high point of this advance is called the
"Mankato Maximum." Another writer, Emiliani, finds that
a sixth expansion of the ice sheet, the "Cochrane Advance,"
took place less than 7,000 years ago (132).
g. There was a sudden, virtually complete disappearance
of the ice sheet (which had, however, according to Flint, been
getting thinner ever since the Tazewell Advance) (375:177).
It disappeared in an extraordinarily short period, as shown
by a postglacial date from Cochrane, Ontario, 6,380 years ago.
h. The significance of the postglacial date from Ontario
(close to the center of the former ice sheet) is increased when
we compare it with the date of the postglacial Climatic Op
timum, which Flint finds to have occurred between 6,000 and
4,000 years ago. The climate during the Optimum, according
to Brooks (52:296-97), averaged about 5 degrees warmer
than at present. There is a very difficult problem here of ac-
counting for the velocity of these events. It is obvious that
the cold glacial climate of North America must have warmed
up to something like the present prevailing temperatures
before it could warm up still further to the point reached
in the Optimum. But if so, could the whole wanning process
2O2 EARTH'S SHIFTING CRUST
have taken place in 380 years? It seems probable that the
Cochrane Advance was local and minor. The Mankato Max-
imum, however, was not. The entire transformation of the
climate must then have taken place in about 2,000 years.
In this short interval a continental icecap disappeared. It
had been growing thinner for a long time, to be sure—for
about 10,000 years, since the Tazewell Advance— but its final
dissolution was sudden. Compared with the usual geological
time concepts, even the period of 10,000 years for the decline
of the ice sheet from the end of the Tazewell Advance is in-
credibly rapid. Horberg, as I have mentioned, has pointed
out that if the radiocarbon method is valid, the rate at which
the ice must have advanced and retreated indicates that geo-
logical processes (especially meteorological processes like
rainfall) must have been greatly accelerated during the ice
age. Now it is easy to show that these processes inevitably
would have been accelerated by a movement of the crust;
we shall return to consider this matter in detail below.
As a matter of fact, it is not necessary to depend wholly
upon radiocarbon dating to establish the extraordinary ve-
locity of the geological events of the ice age. Professor Urry's
method of radioelement dating, used to date the cores ob-
tained by Hough from Antarctica and elsewhere, shows pre-
cisely the same thing: the datings obtained by this method
indicate several rapid glaciations and deglaciations of Ant-
arctica, and correlated world-wide changes of climate. We
will consider these again in Chapter IX.
A third line of evidence tending to the same effect is pre-
sented by Emiliani, who has applied a technique of deter-
mining ancient temperatures of sea water that was developed
by Harold C. Urey. Urey's method is based on an isotope
of oxygen. Emiliani has noted many important temperature
changes in a comparatively short period during the latter
part of the Pleistocene; he has reached the conclusion that
the four known Pleistocene glaciations all occurred in the
last 300,000 years. He agrees essentially with Horberg as to
the date of the beginning of the Wisconsin glaciation (132).
NORTH AMERICA AT THE POLE 2OJ
Assuming the radiocarbon dates to be correct, then, we
find that at the end of the Tazewell Advance there was a
recession, and that despite the readvances the ice gradually
thinned until the ice sheet disappeared. This can be ac-
counted for by the assumption that the crust was in motion,
and that it continued to move slowly during all or most of
the 10,000 years during which the icecap was in intermittent
decline. As I have already pointed out, there is no other
reasonable explanation for the disappearance of the ice sheet.
But the assumption is strengthened by a most remarkable
fact. It would have to be considered probable, as following
naturally from the theory, that as the crust moved there
would be a period, possibly prolonged, when the melting on
the equatorward side of the icecap would be balanced and
even more than balanced by further build-up of the icecap
on the poleward side. Thus, as the Wisconsin icecap moved
southward, build-up of the ice would continue on its north-
ern side. The result would be that the ice center, the center
of maximum thickness, from which the ice sheet would move
out by gravity in all directions, would be 'displaced to the
north. And this is exactly what happened. Coleman writes:
Two important facts have been established by Low, who worked
over the central parts of the Labrador sheet: first, that the center of
the glaciation shifted its position, at one time being in Lat. 51 or
52, later in Lat. 54, and finally in Lat. 55 or 56. Instead of beginning
in the north and growing southward it reversed this direction;
second, that the central area shows few signs of glaciation, so that
the pre-glacial debris due to ages of weathering are almost undis-
turbed. A broad circle around it is scoured clean to the solid
rock. . . . (87:117).
There really could be no more eloquent confirmation of
the southward displacement of the earth's crust. We see veri-
fication here of one of the important mechanisms of displace-
ment as suggested by Campbell, which is that the continuing
build-up of the ice sheet on its poleward side as it moves
away from the pole will be a factor in prolonging the move-
ment. This may, indeed, result in the prolongation of the
204 EARTH'S SHIFTING CRUST
movement until the arrival of an oceanic area (in this case,
the Arctic Ocean) at the pole. As to the second fact that, ac-
cording to Coleman, was established by Low, I shall suggest
an explanation later (Chapter VIII).
). The Cause of the Oscillations of the Ice Sheet and
the Cause of the Climatic Optimum
But what about the alternating phases of retreat and read-
vance of the ice sheet? The retreats can be explained, of
course, by the assumption that the icecap was moving slowly
into lower latitudes with the displacement of the crust. But
how are the readvances to be explained? Up to the present
there has been no explanation for these.
I have already suggested that a corollary of any crust dis-
placement is an increase of volcanic activity. There have
been times in the past, however, when the quantity of vol-
canic action has been extraordinary (231:629). As an exam-
ple of this, there appears to be evidence that in a small area
of only 300 square miles in Scandinavia during Tertiary
times there may have been as many as 70 active volcanoes at
about the same time. Bergquist, who cites the evidence, re-
marks, "Volcanic activity on this scale, erupting through
about 70 channels, and concentrated in a relatively short
period, must have been very impressive" (31:194).
It seems likely that a phase of intense volcanism would be
favored where a sector of the crust was moving toward the
equator, and undergoing stretching (or "extension") together
with widespread fracturing, for we must remember that this
pulling apart of the crust would permit the release of many
pre-existent strains, the upward or downward adjustment of
blocks that had been held out of isostatic adjustment for a
longer or shorter time. There would certainly be a general
rise of igneous matter into millions of new fractures, and
occasionally this could result in overflows at the surface, in-
cluding, as has already been pointed out, vast lava floods.
NORTH AMERICA AT THE POLE 205
A special phase of the volcanism must now attract our at-
tention. Most volcanoes produce dust, sometimes in vast
quantities (87:271). This dust is rapidly distributed through
the atmosphere. The effects of volcanic dust on the climate
have been the subject of intensive studies (231, 375). We must
stop for a moment to summarize the essential results of these
studies.
The fundamental work on the relationship of volcanic
dust to climate is The Physics of the Air, by Humphreys,
which has been cited in earlier chapters. Humphreys shows
that volcanic dust can have a remarkable effect in lowering
temperature. He points out that the effect of the particles
depends upon whether they happen to be more efficient in
intercepting the sun's light and reflecting it back into space
than they are in preventing the radiation of the earth's heat
into outer space. What is important is the size and shape of
the dust particles as compared with the wave lengths of the
radiation. Particles of a given length will have great re-
flecting and scattering power on sunlight, and none on the
radiation of heat from the earth (which, of course, is not
in the form of light). Humphreys concludes that it is neces-
sary to determine the approximate average size of the indi-
vidual grains of floating volcanic dust, as well as the wave
lengths of the radiation involved. He accomplishes this satis-
factorily. After mathematical treatment of the various factors
he concludes: ". . . the shell of volcanic dust, the particles
all being of the size given, is some thirty fold more effective
in shutting out solar radiation than it is in keeping terrestrial
radiation in. . . ." (231:580). He also points out:
. . . The total quantity of dust sufficient ... to cut down the
intensity of solar radiation by 20% ... is astonishingly small— only
i74th part of a cubic kilometer, or the 727th part of a cubic mile. . . .
(231:583).
This, of course, means that the sun's radiation is reduced
to this extent over the whole surface of the earth. It re-
quires only a few days for volcanic dust projected into the
206 EARTH'S SHIFTING CRUST
upper atmosphere to be distributed around the world. Ap-
parently, the amount of dust produced by the eruption of
Mt. Katmai in Alaska in 1912 was sufficient slightly to lower
the temperature of the whole earth's surface for a period of
two or three years (87:270; 231:569). For long-range effects
a continuous series of explosions would be necessary, because
volcanic dust settles out of the atmosphere in periods of the
order of three years. Humphreys presents a great deal of evi-
dence correlating variations in average annual global tem-
peratures through the nineteenth century, with specific vol-
canic eruptions. He establishes the fact that the eruptions
certainly had an important influence.
If this is true of our times, what should we expect to result
from the activation of very great numbers of volcanoes dur-
ing a displacement of the crust? Not only would the tempera-
ture fall, and perhaps very drastically, but continuing vol-
canic outbursts would keep it low. At the same time, the
alternation of periods of massive outbursts with periods of
quiet would produce violent variations of the climate, be-
tween extremes of cold and warmth.
Here we have our explanation of the five or six major
readvances of the Wisconsin ice sheet (there were, appar-
ently, many more minor ones). In all probability, they re-
sulted from the long continuation of massive outbursts of
volcanism. The readvances of the ice are explained by vol-
canism, and the volcanism is explained by the displacement
of the crust.
It is not necessary, however, for us merely to assume with-
out evidence that there must have been unusual volcanic
activity at the end of the ice age. On the contrary, there is a
rather remarkable amount of evidence of excessive volcanism
during the decline of the Wisconsin icecap. It comes from
many parts of the earth. For North America it is particularly
rich. From radiocarbon dating we have learned that during
the last part of the ice age there were active volcanoes in our
northwestern states. One of the greatest eruptions was that
of Mt. Newberry in southern Oregon less than 9,000 years
NORTH AMERICA AT THE POLE
ago (242:23). Other late glacial or early postglacial volcanic
activity in Oregon was reported by* Hansen (199). Farther
south the story is the same:
In Arizona, New Mexico and southern California there are very
fresh looking volcanic formations. The lava flow in the valley of the
San Jose River in New Mexico is so fresh that it lends support to
Indian traditions of a "river of fire" in this locality (235:113).
Volcanic disturbances in South America about 9,000 years
ago have been dated by radiocarbon (242:45). Huntington
reported "lava flows of the glacial period interstratified with
piedmont gravel" in Central Asia (232:168). Ebba Hult de
Geer quoted Franz Firbaz as follows: "The volcanic erup-
tions that produced the Laacher marine volcanic ash are
about 11,000 years old, or a little older. . . ." (108:515).
Hibben suggested that the extinctions of animals in Alaska
at the end of the ice age may have been due to terrific vol-
canic eruptions there, of which the evidence is plentiful
(218). We will return to his account later.
Volcanic dust is not the only important product of volcanic
eruptions. They also produce vast quantities of carbon diox-
ide gas. Tazieff, for example, estimated that in one eruption
he observed in Africa, along with about seventy-eight mil-
lion tons of lava, the volcano emitted twenty billion cubic
yards of gas (416:217), not all of which, of course, was carbon
dioxide.
The carbon dioxide emitted by volcanoes has an important
effect on global temperature, but one quite different from
the effect of the volcanic dust. Being a translucent gas, it does
not interfere with the entrance of sunlight, of radiant heat,
into the atmosphere. But it is opaque to the radiation of
the earth's heat into outer space. A small quantity of the
gas will act effectively to prevent loss of heat from the earth's
surface. A considerable increase in this small percentage will
tend to raise the average temperatures of the earth's surface.
Carbon dioxide differs from volcanic dust also in the fact
that because it is a gas it will not settle out of the atmosphere.
2o8 EARTH'S SHIFTING CRUST
It will remain until, in the course of time, it is absorbed
by the vegetation, or by chemical processes in the rock sur-
faces exposed to the weather. Therefore, as compared with
volcanic dust, carbon dioxide is a long-range factor, and its
effect is opposite to that of the dust.
In any displacement of the crust it follows that massive
outbursts of volcanism must have added to the supply of
carbon dioxide in the air. Its proportion in the atmosphere
must have finally been raised far above normal. In conse-
quence, it is likely that whenever volcanic activity declined
sufficiently to permit a warming of the climate, the high
proportion of carbon dioxide in the air may have acted to
intensify the upward swing of the temperature. This would
have increased the violence of the oscillations of the climate,
and would have accelerated many geological processes.
Evidence that the proportion of carbon dioxide in the air
was, in fact, higher toward the end of the ice age than it is
now is provided by recent studies of gases contained in ice-
bergs. Scholander and Kanwisher, writing in Science, re-
ported that air frozen into these bergs, presumably dating
from the ice age, showed lower oxygen content than air has
at the present time, and theorized:
Possibly this ice was formed as far back as Pleistocene time, when
cold climates may have curbed the photosynthetic activity of green
plants over large parts of the earth, resulting in a slight lowering
of the oxygen content of the air (368:104-05).
The weight of a great deal of evidence presented in this
book is opposed to this particular speculation; we must sup-
pose, on the contrary, that the earth's surface as a whole was
then no colder than it is now, and that just as many plants
were absorbing carbon dioxide and releasing oxygen into
the air then as now. But the same fact— the lower proportion
of oxygen— may perhaps be explained by supposing a higher
proportion of carbon dioxide, especially if we assume a mas-
sive increase in the proportion of that gas in the air.
Another consideration that greatly strengthens this line of
NORTH AMERICA AT THE POLE 2OQ
thinking about the carbon dioxide is that the assumption of
a cumulative increase in the proportion of the gas in the air,
during the movement of the crust and the waning of the ice
sheet, helps to explain not only the extraordinarily rapid
final melting of the ice but also the succeeding Climatic
Optimum.
The Climatic Optimum is the most important climatic
episode since the end of the ice age; the fact of the occur-
rence is well attested, but it is unexplained. Scientists have
been aware that this 2,ooo-year warming of the climate could
have resulted from an increase in the carbon dioxide con-
tent of the air, but this has not been helpful, since hitherto
no way has been found by which to account for an increase
of the required magnitude. No other possible cause of the
warm phase (such as an increase in the quantity of the sun's
radiant heat) has been supported by tangible evidence. It
seems that the assumption of a displacement of the crust
furnishes the first possibility of a solution.
To return, for a moment, to the question of the several
readvances of the ice, it may be asked, Why did the volcanism
occur in massive outbursts separated by quieter periods?
Why was it not continuous through the whole movement of
the crust? Campbell has suggested an answer. It is quite
possible that the fracturing of the crust, necessary to permit
the displacement, was itself spasmodic. We may assume that
when the mounting bursting stress brought to bear on the
crust by the growth of the icecap finally reached the critical
point (that is, the limit of the crust's strength), considerable
fracturing occurred in a rather short time, accompanied by
massive volcanism. The crust would now start to move, and
it would continue to move easily to the distance permitted
by the extent of the fractures so far created. The movement
might then come to a halt, and the accompanying volcan-
ism would tend then to subside. Meanwhile, on the pole-
ward side of the icecap the ice still would be building up,
and the bursting stress resulting from it would again be on
the increase. New fracturing would eventually occur, with
210 EARTH'S SHIFTING CRUST
a new outburst of volcanism, and the movement would be
renewed. In the intervals between phases of intense vol-
canism the dust would settle out of the air, the carbon diox-
ide would take effect, and the climate would rapidly grow
warmer. This warm "interstadial," however, would affect
different sides of the icecap differently; it could cause im-
portant recessions of the ice sheet on the equatorward side,
and at the same time, because of the accompanying rise in
humidity, it could augment the snowfall on the poleward
side.
The crust would continue to move, even though with each
recurring warm period the ice sheet grew thinner, because
the icecap, at each successive stage, would have been moved
farther from the axis of rotation, so that the effects of the
diminishing quantity of the ice would be effectively coun-
terbalanced by the multiplication of the centrifugal effect
per unit volume of the remaining ice (see Chapter XI).
Finally a time would come when the rising temperatures
of the lower latitudes and the accumulation of carbon di-
oxide would so far exceed the refrigerating effects of vol-
canic outbursts that the latter would become impotent to
maintain the icecap. With the reduction of the icecap below
a certain point, the crust would cease to move, volcanic dis-
turbance would decline, the air would be cleared of dust,
and within a short time the accumulated carbon dioxide
would usher in the warm phase of the Optimum. The story
ends with the absorption of the carbon dioxide by the vege-
tation, the reduction of its percentage to normal, and the
establishment of a climate like the present.
4. The Glaciation of Europe
Further confirmation of the position of North America at
the pole during the Wisconsin glaciation comes from Eu-
rope. Radiocarbon dating has revealed some very interesting
NORTH AMERICA AT THE POLE 211
facts about the relationship of the American and Scandi-
navian glaciers.
It has been shown, by Flint (375:175) and others, that
there is a correspondence in the timing of the phases of
advance and retreat of the ice on both sides of the Atlantic.
This is exactly what we should expect, considering that the
causes of the oscillations, the volcanic dust and the carbon
dioxide, were world-wide in their effects.
But despite this synchronism, there is also an important
difference between the two glaciations: it is clear that the
icecap in Europe underwent proportionately greater diminu-
tion with each phase of the recession after the Tazewell
Maximum. The assumption that the glaciations on both
sides of the Atlantic were in all respects precisely contempo-
rary, that they advanced and retreated equally at equal times,
has now produced contradictions of a very glaring character.
It has placed two specialists, Ernst Antevs and Ebba Hult de
Geer, at odds with each other.
The basis of the contradiction is as follows: The late hus-
band of Ebba Hult de Geer, Gerard de Geer, was the author
of the so-called "Swedish Time Scale." This is a method of
geological dating based on countings and comparisons of an-
nually deposited layers of clay (varves) in lakes. De Geer first
developed the method more than a generation ago. In a
number of instances datings established by it have been well
confirmed by the more recent radiocarbon method.
De Geer found that by about 13,000 years ago the Scandi-
navian icecap had retired from Germany and England, and
that the ice front lay across Sweden. It is obvious that its
withdrawal from Germany and England must have started
thousands of years earlier. By 13,000 years ago a large per-
centage of the whole European icecap was gone. In America,
however, the reduction of the Wisconsin icecap had pro-
ceeded nowhere near so far. Twice again, after this, the
American icecap expanded in the Gary and Mankato Ad-
vances. The great icecap, though thinner, still occupied most
of its original area.
212 EARTH'S SHIFTING CRUST
Now, what Dr. Antevs says is that the radiocarbon dates
from America don't make sense, and the radiocarbon method
must be wrong (9:516). He attacks the method because the
rates of withdrawal of the ice which it suggests are to him
fantastic. He complains particularly about the disproportion
in the indicated speeds of withdrawal in America and Eu-
rope. The radiocarbon method has indicated that the Man-
kato Maximum occurred between 11,000 and 10,000 years
ago. This stage has been related chronologically to the so-
called Salpausselka Stage in Europe. Antevs considers this
totally unreasonable, because
This correlation equates a point at less than one-quarter of the
American ice-sheet radius with one at the half way mark in Europe.
Clearly this lop-sided matching cannot be right.
He says, further:
Other implications are equally unreasonable. . . . The Canadian
ice sheet would still have touched Lake Superior when the Scandina-
vian ice sheet had entirely disappeared. . . .
Antevs makes the conflict more explicit, as follows:
The North American ice sheet would still have extended to the
middle of the Great Lakes when the Scandinavian ice sheet had en-
tirely disappeared, for the latter had melted from the Angermanalven
basis by 8550 B.P. [Before the Present], and from Lapland by 7800
B.P., and what is more, the ice would still have lingered in these lakes
while the distinctly warmer Altithermal [Climatic Optimum] came
and went. The ice retreat would have been exceedingly slow during
the Altithermal but extraordinarily rapid during the last 3500 years,
which have been only moderately warm (9:519).
Antevs is therefore driven into a blank rejection of radio-
carbon dating. He insists, in contradiction to all such datings,
that the icecap must have left the Canadian Mattawa Valley
about 13,700 years ago, and that the Mankato Maximum
(which he refers to as the Valders Maximum) must have oc-
curred about 19,000 years ago (9:520). In the discussion in
the pages of the Journal of Geology, between him and Mrs.
de Geer, Mrs. de Geer insists on the high reliability of the
NORTH AMERICA AT THE POLE
radiocarbon method and on the general agreement of the
radiocarbon dates with the dates found by the Swedish Time
Scale. With regard to the date of the Mankato Advance chal-
lenged by Antevs, she says:
The whole method of C14 determinations, however, is taken up
by America's most clever research men and practiced very critically
—most of all the special test at Two Creeks. As they were startled
by the low figures of years obtained, they repeated the investigation
several times. As the same value always recurred, such critical persons
might well have examined eventual deficiencies of the material
before publishing a result regarded generally as unbelievable. Since
such a procedure was not found necessary, the test is probably reliable,
although many others may be doubtful (108:514).
However, Antevs succeeds in making it plain that some of
the late Dr. de Geer's dates, as found by the method of count-
ing clay varves, are inconsistent with radiocarbon dates.
Now here is a shocking conflict between experts, each with
years of experience in the field and direct access to all the
relevant data. How can it be resolved? It seems very likely
that the evidence stressed by both is largely, though not en-
tirely, sound. Yet the difference between them is a major
difference.
This contradiction may be resolved by the simple assump-
tion that North America lay at the pole during the Wiscon-
sin period. By this assumption, Europe would have been a
long way south of the Hudson Bay region. As I pointed out
earlier, the thinner European ice, and the fact that it did not
reach so far south as ice did in America, can be accounted
for in this way. The more rapid retreat of the European
glacier is entirely understandable on the assumption that it
occupied a lower latitude. The simultaneous phases of re-
treat and advance, then, and the faster general retreat of the
European glacier are both understandable.
This problem of the relationship of the American and
European glaciations raises another question. Why was it
that, with a pole in Hudson Bay or western Quebec, Great
Britain and Scandinavia were glaciated at all, since Scan3i-
EARTH'S SHIFTING CRUST
navia at least must then have lain somewhat farther from
the pole than it does now? Furthermore, why did Alaska
then have many great mountain glaciers, but no continuous
ice sheet? The latter problem is intensified by the considera-
tion that the particular movement of the crust that we are
supposing here, while it lowered the latitude of eastern North
America a great deal, must have slightly raised the latitude
of Alaska, especially that of northern Alaska. The reader
can make these relationships clear to himself by referring
now to a globe. We are assuming the displacement to have
occurred along the goth meridian.
The explanation of the glaciation of northwestern Europe
is, I think, as follows. First, the heaviest glaciation of Europe
is not contemporary with the Wisconsin ice sheet, but was
the consequence of an earlier polar position, which will be
discussed further on (Chapter IX). Secondly, the compara-
tively thin European ice sheet of Wisconsin time (which in
Britain consisted really only of discontinuous mountain gla-
ciers) was made possible by a very special combination of
meteorological conditions. In North America a vast icecap
extended eastward from its center near Hudson Bay. Much
of the continental shelf in this whole area was then above
sea level, as, indeed, it should have been to agree with our
general theory, and this was covered by ice. Then the anti-
cyclonic winds, blowing outward in all directions from the
icecap, had only to cross the narrow North Atlantic, raising
moisture from the sea and depositing it upon Scandinavia
and Britain.
At first glance it might seem that a pole in Hudson Bay
would have involved a heavy glaciation of Greenland, but
there are reasons to suppose that it might, on the contrary,
involve a deglaciation. Depending on the precise location of
the pole, parts of Greenland would have lain farther from
it than they do from the present North Pole. Of greater im-
portance, however, is the fact that the Arctic Ocean would
have been a temperate, and even, on the Siberian side, a warm
temperate, sea. It would be likely, in these circumstances,
NORTH AMERICA AT THE POLE 215
that a warm current like the Gulf Stream would have been
flowing at that time out of the Arctic and down the coast of
Greenland. Such a warm current might easily have degla-
ciated the island (or rather, islands). It might, however, have
been deflected from Scandinavia and the British Isles by land
masses in the North Atlantic, to be discussed later on.
If this deglaciation, indeed, reflects what really happened
in Greenland, then there must have been a warm interval in
Europe between the period of massive glaciation, to be dis-
cussed later, and the much less severe glaciation of late Wis-
consin time. The present glaciation of Greenland would have
been the consequence of the passage of the pole from the
Hudson Bay region to its present location, with the refrig-
eration of the Arctic Ocean. The final warming of the cli-
mate both in Europe and in America would have been the
consequence of the disappearance of the North American
icecap, and of the pattern of anticyclonic winds which it had
created.
So far as the glaciation of Alaska is concerned, again, the
climate there was colder than it is now because of the vast
refrigerating effect of the icecap that covered 4,000,000
square miles of the continent. Just as, at present, the Antarc-
tic icecap makes the South Polar region colder than the Arc-
tic (because it is a perfect reflector of the sun's radiant energy
back into space), so then the great Wisconsin icecap meant
that the prevailing temperatures at the center of the ice
sheet (presumably the pole) were much lower than the tem-
peratures prevailing now at the present North Pole, where
no great icecap exists. But, although the intensely cold anti-
cyclonic winds blowing off the Wisconsin icecap made Alaska
colder than it is now, and thereby produced larger glaciers
than exist at present, still these winds blew only over con-
tinuous land, and not over the sea, and so they could not
pick up the moisture required to produce a continuous ice
sheet. This explains why Alaska warmed up at the end of
the North American ice age, even though it actually may
have moved closer to the pole.
2i6 EARTH'S SHIFTING CRUST
Another interesting argument is used by Antevs to buttress
his position against radiocarbon dating. It is based on the
evidence of crustal warping at the end of the ice age. Radio-
carbon dating would, he says, require a fantastic rate of
crustal warping, considered impossible by geophysicists. He
says:
My dating of the Cochrane stage at 11300-10150 B.P. is directly
supported by the fact that long ages were required for the crustal
rise which has occurred in the region since its release from the ice,
At the south end of James Bay the rise of land relative to sea-level
amounts to 600—700 feet. . . . The upward movement of some 650
feet equals the rise of the Scandinavian center of uplift during the
last 8,200 years. Since the rates of modern uplifts are similar, 01
one meter a century in the Scandinavian center, and probably 70-80
centimeters (2.3-2.6 feet) a century at James Bay, the past rates ma}
also have been similar. Since, furthermore, the uplifts in the two
regions may have been essentially equal in general, the regression of
the shore line in the James Bay region by some 650 vertical feet
must have taken several thousand years, perhaps 8,000-10,000
years. . . . (108:520).
However, a displacement of the crust, with America moved
farther than Europe, would solve this problem. Processes of
adjustment of the crust would have a velocity proportional
to the amount of the displacement of the particular area. B)
assumption, North America was displaced more than 2,ooc
miles to the south, but the southward displacement of the
glaciated area in Europe amounted to only about 500 miles,
The assumption of crust displacement offers the first possi-
bility of reconciling the observed rates of crustal warping in
America with geophysical principles.
5. Changes in Sea Level at the End of the Ice Age
There was a remarkable number of changes in the elevation
of lands, and their interconnections, at the end of the ice age
The idea that they can all be explained either by a general
rise of sea level due to the melting of ice or by the isostatic
NORTH AMERICA AT THE POLE 217
rebound of the areas after the ice left is, however, fallacious.
Let us consider, first, the question as to how far the melting
of ice, raising the sea level, can solve the problem.
The new radioelement data from Antarctica, as we have
seen, strongly suggest that the huge total quantity of ice
supposed to have existed during the ice age is an illusion. It
now appears that while the glaciers were at their maximum
in North America a large part of Antarctica was ice-free.
This is the only reasonable interpretation of the Antarctic
data. It is therefore doubtful that the amount of ice then was
very different in amount from that existing now. We have
noted that for about 10,000 years the Wisconsin ice sheet was
growing thinner, until its final disappearance. If this was the
result of the southward movement of the icecap— if North
America was then moving southward— Antarctica must, at
the same time, have been moving into the Antarctic Circle.
Therefore, as the ice sheet gradually thinned in North Amer-
ica, as it withdrew in Europe, the Antarctic icecap must have
been in process of expansion. The water released by the melt-
ing in North America may have been mostly locked up again
in the gathering Antarctic snows.
It follows from this that the process, during a period of
perhaps 10,000 years, was simply one of transfer of ice masses
from the Northern Hemisphere to Antarctica. It is difficult
to say whether the tempos of melting in North America and
of accumulation in Antarctica were always closely in line,
or which may have been faster. No doubt alternations took
place. In consequence, there may have been minor fluctua-
tions of sea level, without a major universal rise.
Yet such a rise of the sea level in some parts of the world
did take place. It has already been pointed out that such
changes must accompany a displacement of the crust. We
have merely to decide which method of accounting for the
facts is most reasonable.
If the rise of the sea was due to melting ice, it should, ad-
mittedly, have been quantitatively proportional to the quan-
tity of the ice that is assumed to have melted. It should, of
2i8 EARTH'S SHIFTING CRUST
course, have been the same in all parts of the world (allow-
ing some differences, perhaps, for vertical movements of the
land locally). It should have been universal— that is, the evi-
dences should be observable everywhere, on all the conti-
nents. There is, however, strong evidence in conflict with
each of these propositions.
The maximum rise in sea level that can be ascribed to the
melting of the Pleistocene ice sheets (assuming that the Ant-
arctic icecap existed contemporaneously with them) is about
300 feet. This is a liberal estimate. Yet, in a recent study,
Fisk and McFarlan show that the sea level during the Wis-
consin glaciation (on American coasts) was 450 feet below
the present level (153:294-96). Moreover, according to them,
this is a minimum estimate, and the probabilities favor a
greater lowering of the sea level in the late Pleistocene. Still
more interesting, they give a chart showing that the lowest
sea level was earlier than 28,000 years ago, or considerably
before the maximum of the Wisconsin ice sheet. This date
was established by radiocarbon (153:281). It can only mean
that the low sea level must be attributed to a cause other
than the withdrawal of water from the ocean to form that
ice sheet.
Furthermore, Fisk and McFarlan show that the sea was
rising 20,000 years ago, before the completion of the massive
Tazewell Advance that carried the Wisconsin icecap to its
maximum size (153:298). Surely, if the sea level were con-
trolled by the glaciers, it should have been falling. Finally,
Fisk and McFarlan show that the sea level had risen to
within 100 feet of its present level by 10,000 years ago. Yet
we know that by that time the Wisconsin glaciation was a
mere shadow of its former self, while the Scandinavian had
virtually ceased to exist. Is it likely that the remnants of these
ice sheets could later have raised the ocean level 100 feet?
The question is rendered even more doubtful by a news
item that comes to me while I write these lines. It is a dis-
patch to the New York Times by John Hillaby, dated from
Sheffield, England, September 2, 1956, giving an account of
NORTH AMERICA AT THE POLE
the meeting of the British Association for the Advancement
of Science. Hillaby describes a paper by Professor Harold
Godwin of Cambridge University in which the professor
gives the results of extensive research into the question of
the date of the separation of England from the Continent.
The date has been found to be 5,000 B.C., or 7,000 years ago.
The report shows that the research work was very thorough.
Now, obviously, by 7,000 years ago the Scandinavian icecap
was long since gone, and the North American ice sheet was
reduced to a few Canadian remnants. Yet only now did the
North Sea bottom sink, and the English Channel become
flooded by the sea. There is evidently something wrong here.
There is a suggestion here that the floodings were produced
by readjustments of the crust, and not by glacial melt water.
There is evidence that the sea rose (or the land subsided)
farther on the western than on the eastern side of the At-
lantic. This, of course, suggests that the development was
not related to an increase of melt water. A good deal of this
evidence was presented years ago by J. Howard Wilson, in
his interesting Glacial History of Nantucket and Cape Cod
(454). Wilson argued that eastern North America must have
stood from 1,000 to 2,500 feet above its present level during
the ice age. If we take the lesser estimate and compare it with
the findings of Fisk and McFarlan (which they give as
minima only) we can see that they are in pretty good agree-
ment. Coleman was in agreement with Wilson, but based
his opinion on the evidence of submarine canyons, which, as
I have already mentioned, may have been created by fractur-
ing of the crust rather than by subaerial erosion and subse-
quent subsidence. Wright and Shaler, however, presented
evidence for a 2,ooo-foot higher elevation of Florida during
the ice age (460), an elevation that would mean a very differ-
ent distribution of land in the Caribbean during the period.
In two different ways this evidence agrees with our dis-
placement theory. First, as the direction of the movement of
the North Atlantic region would hypothetically have been
equatorward, some subsidence of the ocean basin was log-
220 EARTH S SHIFTING CRUST
ically to be expected. Then, as the western side of the At-
lantic was closer to the meridian of maximum displacement,
it would have been displaced through more degrees of lati-
tude, and in consequence there should have been greater
subsidence on the American side of the ocean. Our theory
implies that the Hudson Bay region was moved southward
about 2,000 miles, while at the same time the southward
movement of France amounted to no more than five hun-
dred. The ratio of these distances is about four to one, and
this is very close to the estimated subsidence on the western
side of the Atlantic, of about 1,000 feet, as compared to that
on the eastern side, of less than 300.
From the other side of the globe comes equally impressive
evidence. Wallace argued for a subsidence of at least 600 feet
of the coastlines of Southeast Asia and Indonesia at the end of
the Pleistocene. These areas lie close to the same meridian
of maximum displacement, the goth meridian, which runs
through Labrador, and accordingly they should have been
displaced the same distance as eastern North America, and
the resulting subsidence should have been of the same order.
The Philippines are thought to have become separated from
Asia only some 10,000 years ago; the separation of New
Guinea from Australia and of Java from Sumatra may have
been even more recent. Again, the subsidence may have con-
siderably exceeded 600 feet, which Wallace gives as a mini-
mum (444:24-25). Needless to say, a rise of the sea level of
this extent cannot be explained as the result of melting of
glaciers.
I have already mentioned the fact that some geophysicists
seriously doubt that the rise of the land around the former
glaciated tracts since the end of the ice age is due to isostatic
rebound. It may be more correctly accounted for as a part of
the aftermath of the last displacement of the crust. We have
seen that polar areas are, according to the theory, areas re-
cently moved poleward. Accordingly, they have undergone
compression and uplift, the major part of the uplift being
due to the lag in isostatic readjustment of the crust to the
NORTH AMERICA AT THE POLE 221
variation o£ gravity with latitude (Chapter IV). An equator-
ward movement of such an area would cause extra subsidence
—more than would occur with an area in isostatic equilib-
rium at the start of the movement. And subsequently, iso-
static adjustment would re-elevate the area, but not to its
original, excessive extent. This interpretation of the rebound
of the glaciated tracts has the advantage that it can reconcile
the facts there with the point of view expressed by Gilluly,
and with the data from other parts of the world that so
greatly puzzled Daly.
While there is no evidence that the sea level rose all over
the world and to the same extent everywhere at the end of
the ice age, there is a good deal of evidence that it has fallen
somewhat since. One specialist in this field, Anderson, re-
ported evidence of a fall of sea level amounting to between
100 and 140 feet, and extending over a vast area. He made a
point of emphasizing that this could not be explained by
the postglacial isostatic rebound of the formerly glaciated
tracts of North America and Scandinavia. He is thoroughly
puzzled by what seems to him an inexplicable fact:
. . . what was the cause of a fall in sea-level at a time when it
should have been rising owing to the melting of the ice? (4:493).
This fall of sea level is a matter of very great interest. I
have already suggested that down to the disappearance of the
glaciers in the Northern Hemisphere, the melt water from
them may have pretty well balanced the growth of ice in
Antarctica, so that there was no important change of sea level.
With the disappearance of those northern ice sheets, how-
ever, the situation changed. There was now no longer a
supply of melt water to balance the withdrawal of water to
be locked up in the form of snow in Antarctica; consequently
the sea level had to fall. Even the magnitude of the fall is in
agreement, if we suppose that by about 10,000 years ago,
when the northern icecaps dwindled away, the Antarctic
icecap was half grown. For it is estimated that if the whole
amount of ice now in Antarctica were suddenly melted, it
EARTH'S SHIFTING CRUST
would suffice to raise the sea level between 200 and 300 feet.
Half of it, therefore, would account for the amount of the
fall in sea level noted by Anderson.
There is a widespread impression that the sea level is now
rising all over the world, but this impression seems to be mis-
taken. It is natural, considering the widely publicized opin-
ion that all present-day icecaps are in retreat, that people
should rush to interpret a relative rise of the sea level at a
few localities as indications of a general rise, caused by the
assumed current melting of ice in both hemispheres. An
examination of the data on which this claim is based shows,
however, that the evidence is quite insufficient. I recently
made an inquiry of the United States Coast and Geodetic
Survey regarding this matter and received in reply a com-
munication from Dr. H. E. Finnegan, Chief of the Division
of Tides and Currents, in which he stated:
. . . Long period tide records from control stations maintained
by the Coast and Geodetic Survey show that there has been a rela-
tive rise of sea-level along each of the coasts of the United States.
The rate of rise varies somewhat with the length of series and dif-
ferent regions. During the past 20 years the relative rise of sea-level
along our East Coast has been at the rate of two hundredths of
a foot per year. On our Pacific Coast the rate has been somewhat
less.
In Alaska, the tide records for Ketchikan show no definite change
in sea-level. At certain places farther north, however, the records
indicate a relative fall of sea-level. . . . (152).
This can, I think, be regarded as a summary of the facts
presently known on this subject. It is plain that it does not
add up to any universal rise of the sea level. Not only is no
such rise indicated; exactly the opposite is implied by the
facts. The facts show that different parts of the United States
are subsiding at different rates, that Alaska is not subsiding
at all, and that places farther north are actually rising. What
reason is there to bring the sea into it? A "eustatic" change in
sea level is not indicated by these facts, but differential move-
ments of parts of the continent are. Moreover, the data come
NORTH AMERICA AT THE POLE 22J
from a very small part of the earth's surface. Equally careful
measurements along all the coasts of all the continents would
be necessary to establish the fact of a general rise in sea level.
They could as easily establish that the sea level is falling.
Additional evidences of the fall of the sea level in post-
glacial times are provided by Halle, for the Falkland Islands
(196), by Pollock, for Hawaii (34ga), and by Sayles, for Ber-
muda (366a). Umbgrove, basing his statement on quite other
sources, concludes that "the sea-level has fallen over the
whole world in comparatively recent times*' (430:69).
A quite remarkable bit of evidence comes from Greenland.
There a whale was recently discovered well preserved in the
permafrost (the permanently frozen ground). It was dated by
radiocarbon, and found to be 8,500 years old. It was found
in beach deposits 43.6 feet above the present sea level. The
highest beach in the area was 1 30 feet above the present sea
level. It is hard to see how the elevation of this beach could
be ascribed to isostatic rebound of the crust since the ice age,
for there has been no lightening of the ice load on the crust
in Greenland. How, then, is this frozen whale to be inter-
preted? I think we can accept it as fairly good evidence of a
general fall of sea level resulting from the withdrawal of
water from the oceans to feed the growing Antarctic icecap.
From the Philippines comes additional evidence that in
those areas where the sea level rose at the end of the North
American ice age, the rise was of a magnitude that cannot
be explained on the theory of glacial melt water, but, on the
contrary, requires the assumption that important changes
took place in the crust itself. Warren D. Smith has written:
It must be said that the geological history and structure of the
Philippines, as studied in recent years by both Dr. Dickerson and
myself, seem to indicate that the changes since the Pleistocene in
the Philippines have been profound enough to have caused the
disruption of land bridges and to have brought about the present
isolation of its masses by flooding. . .
We may note that Smith makes no reference to a rise of
sea level because of the melting of glaciers. The subsidence
224 EARTH'S SHIFTING CRUST
of the islands, and their separation from Asia, are attributed
to deformation of the earth's crust itself. Moreover, it is un-
likely that Smith had any conception of how recently these
events occurred. He probably thought of the Pleistocene (and
the ice age) as ending 20,000 or 30,000 years ago. Conse-
quently, the structural changes in the crust that he discusses
seem to have occurred at a rate which, like the unwarping
of the crust in North America discussed by Antevs, is in-
consistent with the speeds of geological change normally
considered by geologists. There appears to be no rational
explanation for such an acceleration of the tempo of geolog-
ical change, except a displacement of the crust.
There is another important problem connected with the
changes in sea level. It seems that many of them occurred in
an abrupt fashion, so suddenly that the continuous cutting
of the coastline by the sea was unable to keep up with the
vertical movement of the land. Brooks refers to numerous
strandlines at elevations of about 90, 126, and 180 feet above
the present sea level, which may be traced over considerable
areas (52:491). It seems reasonable that if the rise of the land
in these localities (or the general fall of the sea) was gradual,
the erosive action of the sea would have been able to keep
extending the beach downward continuously. We would
then have a continuous beach formation extending from 180
feet above the present sea level, down to the present sea
margin. We have, on the contrary, a series of completely
distinct elevated beaches. It would seem that the changes in
elevation were comparatively rapid.
There is a possibility that this phenomenon is connected
with the irregularities of the process of crust displacement
referred to above. If the interstadials and the repeated re-
advances of the glaciers during the North American ice age
resulted from the process I have described, the same process
of storage and sudden release of stresses in the moving crust
could easily account for abrupt changes in the elevation of
sections of the crust. I am not suggesting that they occurred
in periods of a few days or hours. The facts would be satisfied
NORTH AMERICA AT THE POLE 225
by the assumption that they occurred in periods of the order
of a few centuries. But it is clear that these beaches cannot be
accounted for by a theory of postglacial upward adjustment,
for there is no reason why this adjustment should have taken
place in jumps. It would have been, by its nature, a gradual
and even process.
6. Darwin's Rising Beachline in South America
A singularly impressive piece of evidence for a recent dis-
placement of the crust may be found in the journal of
Charles Darwin. Sir Archibald Geikie summarized Darwin's
findings thus:
On the west coast of South America, lines of raised terraces con-
taining recent shells have been traced by Darwin as proofs of a great
upheaval of that part of the globe in modern geological time. The
terraces are not quite horizontal but rise to the south. On the frontier
of Bolivia they occur from 60 to 80 feet above the existing sea-level,
but nearer the higher mass of the Chilean Andes they are found at
one thousand, and near Valparaiso at 1300 feet. That some of these
ancient sea margins belong to the human period was shown by Mr.
Darwin's discovery of shells with bones of birds, ears of maize, plaited
reeds and cotton thread, in some of the terraces opposite Callao
at a height of 85 feet. Raised beaches occur in New Zealand and indi-
cate a greater change of level in the southern than in the northern
end of the country. . . . (170:288).
If we attempt, by analyzing this evidence in accordance
with the assumptions of the displacement theory, to recon-
struct the course of events, we reach the following conclu-
sions: Since the evidence of human occupation is found at an
elevation of 85 feet, it seems reasonable to suppose that a fall
of the sea level of that extent may have occurred within his-
torical times. On the other hand, the continuously rising
strandline down the coast to Valparaiso, continued in New
Zealand, indicates a tilting of the earth's crust, involving.
South America and New Zealand, but not involving a general
change in the sea level. The magnitude of the upheaval sug-
226 EARTH'S SHIFTING CRUST
gests that it may have occurred earlier than the 85-foot gen-
eral fall in sea level, and may have required much more time.
The 85-foot fall in the general sea level we may explain as
the result of the withdrawal of water to Antarctica. The up
tilting of the continent may be seen as the result of its pole-
ward displacement.
The effect postulated by Gutenberg, to account for uplift
of areas displaced poleward, cannot account for the tilting,
but another effect may. This is the increasing compression
of the poleward-moving sector as the result of the progressive
shortening of the radius and circumference of the earth in
the higher latitudes. The compressions resulting from this
have been discussed. They result inevitably from the increas-
ing arc of the surface and the increasing convergence of the
meridians.
VIII : THE GREAT EXTINCTIONS
When this theory was first presented to a group of scientists
at the American Museum of Natural History, on January 27,
1955, Professor Walter H. Bucher, former President of the
Geological Society of America, made an interesting observa-
tion. I had presented evidence to support the contention that
North America had been displaced southward and Antarctica
had been moved farther into the Antarctic Circle by the
movement of the crust at the end of the ice age. Professor
Bucher pointed out that, if this were so, there must have
been an equal movement of the crust northward on the op-
posite side of the earth. He asked me whether there was evi-
dence of this. I said I thought there was. I am presenting the
evidence here.
7. The Extinction of the Mammoths
The closing millennia of the ice age saw an enormous mortal-
ity of animals in many parts of the world. Hibben estimated
that as many as 40,000,000 animals died in North America
alone (212:168). Many species of animals became extinct, in-
cluding mammoths, mastodons, giant beaver, sabertooth cats,
giant sloths, woolly rhinoceroses. Camels and horses appar-
ently became extinct in North America then or shortly after-
wards, although one authority believes a variety of Pleistocene
horse has survived in Haiti (365). The paleontologist Scott is
enormously puzzled both by the great climatic revolution
and by its effects:
The extraordinary and inexplicable climatic revolutions had a
profound effect upon animal life, and occasioned or at least ac-
companied, the great extinctions, which, at the end of the Pleistocene,
228 EARTH'S SHIFTING CRUST
decimated the mammals over three-fifths of the earth's land sur-
face (37^75)'
No one has been able to explain these widespread extinc-
tions. I shall attempt to explain them as consequences of the
last displacement of the crust, but, since the extinctions took
place both in North America and in Asia— that is, both in the
area presumably moved southward and in the area presum-
ably moved northward, I shall concentrate first on Asia.
There we shall find no difficulty in producing evidence to
show that the climate of eastern Siberia grew colder as North
America grew warmer, just as the theory requires.
Among all the animals that became extinct in Asia, the
mammoth has been the most studied. This is because of its
size; because of the great range of its distribution, all the
way from the New Siberian Islands in the Arctic Ocean,
across Siberia and Europe, to North America; because pic-
tures of it drawn by primitive man have been found in the
caves of southern France and Spain; but most of all, perhaps,
because well-preserved bodies of mammoths have been found
frozen in the mud of Siberia and Alaska. Ivory from these
frozen remains has provided a supply for the ivory trade of
China and Central Europe since ancient times.
A study of the reports on the frozen mammoths reveals
some very remarkable facts. In the first place, they increase
in numbers the farther north one goes, and are most numer-
ous in the New Siberian Islands, which lie between the Arc-
tic coast of Siberia and the pole. Secondly, they are accom-
panied by many other kinds of animals. Thirdly, although
ivory is easily ruined by exposure to the weather, uncounted
thousands of pairs of tusks have been preserved in perfect
condition for the ivory trade. A fourth point is that the
bodies of many mammoths and a few other animals have
been preserved so perfectly (in the frozen ground) as to be
edible today. Finally, astonishing as it may seem, it is not
true that the mammoth was adapted to a very cold climate.
I shall first take up this question of the mammoth's alleged
adaptation to cold.
THE GREAT EXTINCTIONS 229
2. The Mammoth's Adaptation to Cold
It has long been taken for granted, without really careful
consideration, that the mammoth was an Arctic animal. The
opinion has been based on the mammoth's thick skin, on
its hairy coat, and on the deposit of fat usually found under
the skin. Yet it can be shown that none of these features
mean any special adaptation to cold.
To begin with the skin and the hair, we have a clear
presentation of the facts by the French zoologist and derma-
tologist H. Neuville. His report was published as long ago
as 1919 (325). He performed a comparative microscopic study
of sections of the skin of a mammoth and that of an Indian
elephant, and showed that they were identical in thickness
and in structure. They were not merely similar: they were
exactly the same. Then, he showed that the lack of oil glands
in the skin of the mammoth made the hair less resistant to
cold and damp than the hair of the average mammal. In
other words, the hair and fur showed a negative adaptation
to cold. It turns out that the common, ordinary sheep is
better adapted to Arctic conditions:
We have . . . two animals very nearly related zoologically, the
mammoth and the elephant, one of which lived in severe climates
while the other is now confined to certain parts of the torrid zone.
The mammoth, it is said, was protected from the cold by its fur
and by the thickness of its dermis. But the dermis, as I have said, and
as the illustrations prove, is identical in the two instances; if
would therefore be hard to attribute a specially adaptive function
to the skin of the mammoth. The fur, much more dense, it is true,
on the mammoths than on any of the living elephants, nevertheless
is present only in a very special condition which is fundamentally
identical in all of these animals. Let us examine the consequences
of this special condition, consisting, I may repeat, in the absence of
cutaneous glands. The physiological function of these glands is very
important. [Neuville's footnote here: It is merely necessary to men-
tion that according to the opinion now accepted, that of Unna,
the effect of the sebum is to lubricate the fur, thus protecting it
against disintegration, and that of the sweat is to soak the epidermis
230 EARTH'S SHIFTING CRUST
with an oily liquid, protecting it also against desiccation and dis-
integration ... the absence of the glandular secretions puts the
skin in a condition of less resistance well known in dermatology.
It is superfluous to recall that the sebaceous impregnation gives the
fur in general its isolating properties and imparts to each of its
elements, the hairs, its impermeability, thanks to which they resist
with a well-known strength all disintegrating agents, and notably
those which are atmospheric. Everyone knows to what degree the
presence of grease produced by the sebaceous glands renders wool
resistant and isolating, and to what degree the total lack of this fatty
matter lessens the value of woolen goods. . . .] (325:331-33).
Neuville, then, points out in the foregoing passage both
that the mammoth lacks sebaceous glands and that the oil
from these glands is an important factor in the protection of
an animal against cold. It is probable, also, that protection
from damp is more important than protection from low tem-
perature. Oil in the hair must certainly impede the penetra-
tion of damp. The hair of the mammoth, deprived of oil,
would seem to offer poor protection against the dampness
of an Arctic blizzard. Sanderson has pointed out that thick
fur by itself means nothing: a lot of animals of the equatorial
jungles, such as tigers, have a thick fur (365). Fur by itself
is not a feature of adaptation to cold, and fur without oil, as
Neuville points out so lucidly, is, if anything, a feature of
adaptation to warmth, not cold.
The question of the importance of oily secretions from the
skin for the effectiveness of resistance of fur or hair to cold
and damp is, however, highly involved. Very many inquir-
ies directed to specialists in universities, medical schools,
and research institutes over a period of more than five years
failed to elicit sufficiently clear and definite answers until,
finally, Dr. Thomas S. Argyris, Professor of Zoology at
Brown University, referred me to the Headquarters Research
and Development Command of the United States Army.
This agency, in turn, very kindly referred me to the British
Wool Industries Research Association. I addressed an in-
quiry to them, regarding the effects of natural oil secre-
THE GREAT EXTINCTIONS 231
tions from the skin on the preservation of wool. They replied
in general confirmation of Neuville:
. . . Those interested in wool assume that the function of the
wool wax is to protect the wool fibres from the weather and to
maintain the animal in a dry and warm condition. Arguments in
this direction are of course mainly speculative. We do know, however,
that shorn wool in its natural state can be stored and transported
without entanglement (or felting) of the fibres, while scoured wool
becomes entangled so that, during subsequent processing, fibre
breakage at the card is significantly increased. It seems reasonable,
therefore, to assume that the wool wax is responsible not only for
conferring protection against the weather but also for the mainte-
nance of the fleece in an orderly and hence more efficacious state
(458).
It appears that there has been no scientific study of the pre-
cise points at issue here; no one has measured in any scien-
tific way the quantitative effect of oily secretions in keeping
heat in or moisture out. Despite this fact, however, we are
at least justified, on the basis of the facts cited above, in re-
jecting the claims advanced for the hair of the mammoth as
an adaptive feature to a very cold climate.
Neuville goes on to destroy one or two other arguments
in favor of the mammoth's adaptation to cold:
... It has been thought that the reduction of the ears, thick and
very small relatively to those of the existing elephants, might be so
understood in this sense; such large and thin ears as those of the
elephants would probably be very sensitive to the action of cold.
But it has also been suggested that the fattiness and peculiar form
of the tail of the mammoth was an adaptive character of the same
kind; however, it is to the fat rumped sheep, animals of the hot
regions, whose range extends to the center of Africa, that we must
go for an analogue to the last character.
It is therefore, only thanks to entirely superficial comparisons
which do not stand a somewhat detailed analysis, that it has been
possible to regard the mammoth as adapted to the cold. On account
of the peculiar character of the pelage the animal was, on the con-
trary, at a disadvantage in this respect (325:331-33).
There remains the question of the layer of fat, about
three inches thick, which is found under the skin of the
EARTH'S SHIFTING CRUST
mammoth. This fat is thought to have provided insulation
against the bitter cold of the Siberian winter.
The best opinion of physiologists is opposed to the view
that the storage of fat by animals is a measure of self-pro-
tection against cold. The consensus is, on the contrary, that
large fat accumulation testifies chiefly to ample food supply,
obtainable without much effort, as, indeed, is the case with
human beings. Physiologists agree that resistance to cold is
mainly a question of the metabolic rate, rather than of in-
sulation by fat. Since the length of capillaries in a cubic
inch of fat is less than the length of capillaries in a cubic
inch of muscle, blood circulation would be better in a thin
animal. We might ask the question, Which would be more
likely to survive through a Siberian winter, a man burdened
with fifty or a hundred pounds of surplus fat or a man of
normal build who was all solid muscle, assuming that winter
conditions would mean a hard struggle to obtain food? Dr.
Charles P. Lyman, Professor of Zoology at Harvard, re-
marked, regarding this question of fat:
It is true that many animals become obese before the winter sets
in, but for the most part it seems likely that they become obese
because they have an ample food supply in the fall, rather than
that they are stimulated by cold to lay down a supply of fat. Cold
will ordinarily increase the metabolic rate of any animal which means
that it burns up more fuel in order to maintain its ordinary weight,
to say nothing of adding weight in the form of fat. The amount of
muscular activity in the daily life of either type of elephant is
certainly just as important as the stimulus of cold as far as laying
down a supply of fat is concerned (284).
This statement suggests that there is no basis for the as-
sumption that the fat of the mammoths adapted them to an
Arctic climate. On the other hand, it is quite true that the
storage of fat in the fall may help animals to get through
the winter when food is scarce. The winter does not, how-
ever, have to be an Arctic winter. A white* such as we have
in temperate climates is quite cold enough to cut the avail-
able food supply for herbivorous animals. It seems that under
THE GREAT EXTINCTIONS
favorable circumstances even the African and Indian ele-
phants accumulate quite a lot of fat. F. G. Benedict, in his
comprehensive work on the physiology of the elephant, con-
siders it a fatty animal (27).
The resemblances between the mammoth and the Indian
elephant extend further than the identity of their skins in
thickness and structure, and the fact that they were both fatty
animals. Bell suggests that they were only two varieties of the
same species:
Falconer insists on the importance of the fact that throughout the
whole geological history of each species of elephant there is a great
persistence in the structure and mode of growth of each of the
teeth, and that this is the best single character by which to distinguish
the species from one another. He finds, after a critical examination
of a great number of specimens, that in the mammoth each of the
molars is subject to the same history and same variation as the cor-
responding molar in the living Indian elephant (25).
It is clear that the similarities in the life histories of each
of the teeth of these two animals are more important than the
differences in the shapes of the teeth, which were such as
might easily occur in two varieties of the same species. It
cannot be denied that two varieties of the same species may
be adapted to different climates, but it must be conceded
that the adaptation of two varieties of the same species, one
to tropical jungles and the other to Arctic conditions, is
against the probabilities.
3. The Present Climate of Siberia
, are ar
The people who lay the greatest st^ rudde**16 adaptation of
the mammoth to cold ignore the ouier a^mals that lived
with the mammoths. Yet we know that along with the mil-
lions of mammoths, the northern Siberian plains also sup-
ported vast numbers of rhinoceroses, antelope, horses, bison,
and other herbivorous creatures, while a variety of carnivores,
including the sabertooth cat, preyed upon them. What good
EARTH'S SHIFTING CRUST
does it do to argue that the mammoth was adapted to cold
when it is impossible to use the argument in the case of sev-
eral of the other animals?
Like the mammoths, these other animals ranged to the far
north, to the extreme north of Siberia, to the shores of the
Arctic Ocean, and yet farther north to the Lyakhov and New
Siberian Islands, only a very short distance from the pole.
It has been claimed that all the remains on the islands may
have been washed there from the mouths of the Siberian
rivers by spring floods; I shall consider this suggestion a little
later.
So far as the present climate of Siberia itself is concerned,
Nordenskjold made the following observations of monthly
averages of daily Centigrade temperatures during the year
along the Lena River (334):
January —48.9 July 154
February — 47.2 August 11.9
March — 33.9 September 2.3
April — 14 October — 13.9
May — 0.14 November — 39.1
June 13.4 December — 45.1
The average for the whole year was — 16.7. Since zero in the
Centigrade scale is the freezing point of water, it will be
seen that only one or two months in the year are reasonably
^ee from frost. Even so, there must be frequent frosts in
'jr . notwithstanding occasional high midday temperatures.
No (3!uai H was knwledge of these conditions that caused
the great fc^ jf modern geology, Sir Charles Lyell, to
remark that it ->st$ tha tofl^ J* be impossible for herds of
mammoths and t.the m^ .v3 *° subsist, throughout the year,
even in the southern part: of Siberia. . . .
If this is the case with Siberia, what are we to think when
we contemplate the New Siberian Islands? There the re-
mains of mammoths and other animals are most numerous
of all. There Baron Toll found remains of a sabertooth cat,
and a fruit tree that had been ninety feet high when it was
THE GREAT EXTINCTIONS
standing. The tree was very perfectly preserved in the perma-
frost, with its roots and seeds (113:151). Toll claimed that
green leaves and ripe fruit still clung to its branches. Yet, at
the present time, the only representative of tree vegetation
on the islands is a willow that grows one inch high.
Now let us return to the question of whether all these re-
mains were floated out to the islands on spring floods. Let us
begin with a backward view at the history of these islands.
Saks, Belov, and Lapina point to evidence that there were
luxuriant forests growing on the New Siberian Islands in
Miocene and perhaps Pliocene times (364). At the beginning
of the Pleistocene the islands were connected with the main-
land, and the mammoths ranged over them. In the opinion
of these writers the vast numbers of mammoth remains on
Great Lyakhov Island indicate that they took refuge on the
island when the land was sinking (364:4, note). There is no
evidence that they were washed across the intervening sea.
The improbabilities in this suggestion of transportation of
these hundreds of thousands of animal bodies across the
entire width of the Nordenskjold Sea, for a distance of more
than 200 miles from the mouth of the Lena River, are simply
out of all reason. Let us see exactly what is involved.
First, we should have to explain why the hundreds of thou-
sands of animals fell into the river. To be sure, they did not
fall in all at once; nevertheless, they must have had the habit
of falling into the river in very large numbers, because only
one body in a very great many could possibly float across 200
miles of ocean. Of those that floated at all only a few would
be likely to float in precisely the correct direction to reach
the islands. Islands, even large ones, are amazingly easy to
miss even in a boat equipped with a rudder and charts. The
Lena River has three mouths, one of which points in a direc-
tion away from the islands. The two other mouths face the
islands across these 200 miles of ocean. Occasionally, a piece
of driftwood might float across the intervening sea. Occa-
sionally, perhaps, an animal— if for some reason it did not
happen to sink, if it were not eaten by fishes— might be
236 EARTH'S SHIFTING CRUST
washed up on the shore of one of the islands. It seems proba-
ble that only an incredibly powerful current could transport
the body of a mammoth across 200 miles of ocean.
But let us suppose that somehow the animals are trans-
ported across the ocean. What then? The greatest of the New
Siberian Islands is about 150 miles long and about half as
wide. Not one single account of the explorations on these
islands has mentioned that the animal remains are found
only along the beaches. They are obviously found also in the
interior. Are we to suppose that the floods of the Lena River
were so immense that they could inundate the New Siberian
Islands, 200 miles at sea? It is safe to say that all the rivers
of Europe and Asia put together, at full flood, would fail to
raise the ocean level 200 miles off the coast by more than a
few inches at most.
But, again, let us suppose that the remains were merely
washed to the present coasts, and not into the interior. How
then were they preserved? How were hundreds of thousands
of mammoths placed above high-water mark? Storms, no
doubt, but whatever storms can wash up, other storms can
wash away. No accumulation of anything occurs along the
coasts because of storms. All that storms can do is to destroy;
they can grind up and destroy anything. And they would
have ground up and destroyed all the bodies, including, of
course, the go-foot fruit tree with its branches, roots, seeds,
green leaves, and ripe fruit.
I think it is plain that the only reason suggestions of this
kind are advanced is that there is need to support some
theory that has been developed to explain some other part of
the evidence, some local problem. Moreover, there is need,
always need, to discredit the evidence that argues for drastic
climatic changes.
Naturally, the knowledge that the Arctic islands, though
they are now in polar darkness much of the year, were in
very recent geologic times able to grow the flourishing
forests of a temperate climate, eliminates any need to in-
sist that they were always as cold as they are today. Thus,
THE GREAT EXTINCTIONS 237
it is not a question at all of whether the climate grew
colder, but merely a question of when the change oc-
curred. I have already discussed the evidence showing that
it occurred (for the last time, anyway) when North Amer-
ica moved southward from the pole.
Campbell has contributed a suggestion with regard to
the alleged floating of hundreds of thousands of bodies
across the Nordenskjold Sea. He notes that bodies ordinarily
float because of gas produced by decomposition. Decomposi-
tion is at a minimum in very cold water, and therefore bodies
ordinarily do not float in very cold water. As an example of
this he points to a peculiarity of Lake Superior. The waters
of this lake are very cold. This may be because they are sup-
plied, as some people think, by underground springs from
the Rocky Mountains, far away. And there is an old saying
in the lake region that "Lake Superior never gives up its
dead." But the Arctic Ocean is as cold as the springs fed by
the glaciers of the Rockies. The water of the Lena would
not be warm even in midsummer, but during the spring
floods— when the Lena would be swollen with the melt water
of the winter snows— the water at such times would be frigid,
and the bodies of animals drowned in it would not decom-
pose, nor would they float. They would tend to sink, instead,
into the nearest hole, and never come to the surface.
4. A Sudden Change of Climate?
We may reasonably conclude that the climate of Siberia
changed at the end of the Pleistocene, and that it grew colder.
Our problem is to discover what process of change was in-
volved. On the one hand, our theory of displacement of the
crust involves a considerable period of time, and a gradual
movement; on the other hand, the discovery of complete
bodies of mammoths and other animals in Siberia, so well
preserved in the frozen ground as to be in some cases still
edible, seems to argue a cataclysmic change.
238 EARTH'S SHIFTING CRUST
To those who, in the past, have argued for a very sudden
catastrophe, the specialists in the field have offered opposing
theories to explain the preservation of the bodies. One of
these was that as the mammoths walked over the frozen
ground, over the snow fields, they may have fallen into pits
or crevasses and been swallowed up and permanently frozen.
Or, again, they might either have broken through river ice
and been drowned, or they might have got bogged while
feeding along the banks.
There is no doubt that a certain number of animals could
have been put into the frozen ground in just the manner sug-
gested above. That this is the explanation for the preserva-
tion of the mammoths' bodies generally, however, is unlikely
for a number of reasons.
It is not generally realized, in the first place, that it is not
merely a matter of the accidental preservation of eighty-odd
mammoths and half a dozen rhinoceroses that have been
found in the permafrost. These few could perhaps be ac-
counted for by individual accidents, provided, of course, that
we agreed that the animals concerned were Arctic animals.
The sudden freezing and consequent preservation of the
flesh of these animals might be thus explained. But there is
another factor of great importance, which has been con-
sistently neglected. It has been overlooked that meat is not
the only thing that has to be frozen quickly in order to be
preserved. The same is true of ivory. Ivory, it appears, spoils
very quickly when it dries out.
Tens of thousands of skeletons and individual bones of
many kinds of animals have been discovered in the perma-
frost. Among them have been found the enormous numbers
of mammoths' tusks already mentioned. To be of any use
for carving, tusks must come either from freshly killed ani-
mals or have been frozen very quickly after the deaths of the
animals, and kept frozen. Ivory experts testify that if tusks
are exposed to the weather they dry out, lose their animal
matter, and become useless for carving (280:361-66).
According to Lydekker, about 20,000 pairs of tusks, in
THE GREAT EXTINCTIONS 239
perfect condition, were exported for the ivory trade in the
few decades preceding 1899, yet even now there is no end
in sight. According to Digby, about a quarter of all the mam-
moth tusks found in Siberia are in good enough condition
for ivory turning (113:177). This means that hundreds of
thousands of individuals, not merely eighty or so, must have
been frozen immediately after death, and remained frozen.
Obviously, it is unreasonable to attempt to account for these
hundreds of thousands of individuals by the assumption of
such rare individual accidents as have been suggested above.
Some powerful general force was certainly at work. Lydekker
gives many hints of the nature of this force in the following
passage:
... In many instances, as is well known, entire carcasses of the
mammoth have been found thus buried, with the hair, skin and flesh
as fresh as in frozen New Zealand sheep in the hold of a steamer.
And sleigh dogs, as well as Yakuts themselves, have often made a
hearty meal on mammoth flesh thousands of years old. In instances
like these it is evident that mammoths must have been buried and
frozen almost immediately after death; but as the majority of the
tusks appear to be met with in an isolated condition, often heaped
one atop another, it would seem that the carcasses were often broken
up by being carried down the rivers before their final entombment.
Even then, however, the burial, or at least the freezing, must have
taken place comparatively quickly as exposure in their ordinary con-
dition would speedily deteriorate the quality of the ivory (280:363).
He continues:
How the mammoths were enabled to exist in a region where their
remains became so speedily frozen, and how such vast quantities of
them became accumulated at certain spots, are questions that do not
at present seem capable of being satisfactorily answered; and their
discussion would accordingly be useless. . . . (280:363).
Lydekker was not alone in feeling the futility of considering
these mysterious facts. For many years, in this field as in
others, there has been a tendency to put away questions that
could not be answered. However, we shall return to his state-
ment. I shall try to show later on how all the details of the
phenomena he describes can be made understandable. For
240 EARTH'S SHIFTING CRUST
the moment, I would like to point out simply that some sort
of abrupt climatic change is required. This conclusion is re-
inforced by the results of recent research in the frozen foods
industry. This has produced evidence that throws additional
doubt on the theory of the preservation of the bodies of
mammoths by individual accidents. It seems that the preser-
vation of meat by freezing requires some rather special condi-
tions. Herbert Harris, in an article on Birdseye in Science
Digest, writes:
What Birdseye had proved was that the faster a food can be frozen
at "deep" temperatures of around minus 40 degrees Fahrenheit, the
less chance there is of forming the large ice crystals that tear down
cellular walls and tissues leaving gaps through which escape the
natural juices, nutriment and flavor (202:3).
Harris quotes one of Birdseye's engineers as saying:
. . . take poultry giblets; they can last eight months at 10 below zero,
but "turn" in four weeks above it. Or lobster. It lasts 24 months at
10 below but less than twenty days at anything above. . . . (202:5).
In the light of these statements the description of the
frozen mammoth flesh given by F. F. Herz is very illumi-
nating. Quoted by Bassett Digby in his book on the mam-
moth, Herz said that "the flesh is fibrous and marbled with
fat." It 'looks as fresh as well frozen beef." And this remark
is made of flesh known to have been frozen for thousands of
years! Some people have reported that they have been made
ill by eating this preserved meat, but occasionally, at least, it
is really perfectly edible. Thus Mr. Joseph Barnes, former
correspondent of the New York Herald Tribune, remarked
on the delicious flavor of some mammoth meat served to him
at a dinner at the Academy of Sciences in Moscow in the
i93o's (24).
What Birdseye proved was that meat to remain in edible
condition must be kept very cold—not merely frozen, but at
a temperature far below the freezing point. What the edible
mammoth steaks proved was that meat had been so kept in
at least a few cases for perhaps 10,000 to 15,000 years in the
THE GREAT EXTINCTIONS 241
Siberian tundra. It is reasonable to suppose that the same
cause that was responsible for the preservation of the meat
also preserved the ivory; and therefore that tens or hundreds
of thousands of animals were killed in the same way.
How can such low temperatures for the original freeze be
reconciled with the idea of individual accidents unless at
least the animals died in the middle of the winter? It is quite
certain that such temperatures could never have prevailed
at the surface or in mudholes during "spring freshets." Ripe
seeds and buttercups, found in the stomach of one of the
mammoths, to be discussed later, showed that his death took
place in the middle of the summer. It is obvious that during
the summer the temperature at the top of the permafrost
zone was and is 32° F. or o° Centigrade, neither more nor
less, since by definition that is where melting begins. And
from that point down there would be only a relatively
gradual fall in the prevailing temperature of the permafrost.
Even if mammoths died in the winter, it is difficult to see
how very many of them could have become well enough
buried to have escaped the warming effects of the thaws of
thousands of springs and summers, which would have rotted
both the meat and the ivory, unless there was a change of
climate.
The theory that mammoths may have been preserved by
falls into pits or into rivers encounters further objections.
Tolmachev, the Russian authority, pointed out that the re-
mains are often found at high points— on the highest points
of the tundra (422:51). He notes that the bodies are found
in frozen ground, and not in ice, and that they must have
been buried in mud before freezing. This presents a serious
problem because, as he says,
... As a matter of fact, the swamps and bogs of a moderate climate
with their treacherous pits, in northern Siberia, owing to the perma-
nently frozen ground, could exist only in quite exceptional conditions
(422:57)-
Ho worth remarked on this same problem:
242 EARTH'S SHIFTING CRUST
While it is on the one hand clear that the ground in which the
bodies are found has been hard frozen since the carcasses were en-
tombed, it is no less inevitable that when these same carcasses were
originally entombed, the ground must have been soft and unfrozen.
You cannot thrust flesh into hard frozen earth without destroying it
Since Tolmachev can think of no other solution to this
problem, he finds himself forced to conclude that the mam-
moths got trapped in mud when feeding on river terraces.
We have seen that this conflicts seriously with the conditions
of temperature required for the preservation of the meat,
whether they were feeding on the terraces during the sum-
mer, when, presumably, the fresh grass supply would be
available there, or whether they were shoving aside the heavy
snowdrifts during the winter to attempt to get at the dead
grass below. For in either case they would fall into unfrozen
water, the temperature of which could not be lower than 32°
Fahrenheit. Furthermore, if this is the way it happened, why
are the animals often found on the highest point of the
tundra?
Thus we see that the further we get into this question the
thornier it becomes. We shall have, for one thing, to face the
problem of the apparently sudden original freeze. How sud-
den, indeed, must it have been? How can we account for it
on the assumption of a comparatively slow displacement of
the earth's crust? So far as the first question is concerned,
recent research has contributed interesting new data.
Research on the mechanics of the freezing process and its
effects on animal tissues has been carried forward consider-
ably since the experiments conducted by Birdseye's engi-
neers. In a recent article in Science, Meryman summarizes
the recent findings. These are based on extremely thorough
laboratory research, and they modify, to some extent, the
Birdseye findings.
Meryman shows that initial freezing at deep temperatures
is not required for the preservation of meat. On the contrary,
such sudden deep freeze may destroy the cells. He remarks,
THE GREAT EXTINCTIONS 24$
"Lovelock considers — 5° C. as the lowest temperature to
which mammalian cells may be slowly frozen and still sur-
vive." Furthermore, the tissues survive gradual freezing very
well:
In most, if not all, soft tissue cells there is no gross membrane rup-
ture by slow freezing. Even though it is frozen for long periods of
time, upon thawing the water is reimbibed by the cells, and their
immediate histological appearance is often indistinguishable from the
normal.
It appears that what damages the cells is dehydration, caused
by the withdrawal of water from them to be incorporated in
the ice. This process goes on after the initial freezing:
. . . The principal cause of injury from slow freezing is not the
physical presence of extracellular ice crystals, but the denaturation
incurred by the dehydration resulting from the incorporation of all
free water into ice (304:518-19).
There are only two known ways, according to Meryman, to
prevent this damage. First, ". . . the temperature may be
reduced immediately after freezing to very low, stabilizing
temperatures." The other way is artificial; it consists of using
glycerine to bind water in the liquid state, preventing freez-
ing.
Meryman shows that once the temperature has fallen to
a very low point, it must remain at that point if the frozen
product is to escape serious damage. The reason for this is
that except at these low temperatures, a recrystallization
process may take place in ice, in which numerous small
crystals are combined into large ones. The growth of the
large crystals may disrupt cells and membranes. He remarks:
At very low temperatures, recrystallization is relatively slow, and
equilibrium is approached while the crystals are quite small. At
temperatures near the melting point, recrystallization is rapid, and
the crystals may grow to nearly visible size in less than an hour (304:
518).
I am reminded, in writing these lines, of my experience in
truck gardening. In trying to reduce damage from frost, I
244 EARTH'S SHIFTING CRUST
often resorted to a method that was effective but mysterious,
for I could not understand why it worked. I learned that if
the vegetables got frosted— even heavily frosted—they would
not be seriously damaged if I could manage to get out before
sunrise and thoroughly hose them off, washing away the
frost. If, however, the sun should rise before I was finished,
the unwashed vegetables would be damaged. It would seem,
according to the explanation given by Meryman, that the
frost damage was the result of recrystallization of the ice that
had formed within the vegetable fibers. Small crystals, grow-
ing into large ones in the hour or so before the sun was up
far enough to melt them, evidently caused the damage.
It follows, from this analysis of the mechanics of freezing,
that the preservation of mammoth meat for thousands of
years may be accounted for by normal initial freezing, fol-
lowed by a sharp fall in temperature. Whenever the meat
was preserved in an edible condition the deep freeze must
have been uninterrupted; there must have been no thaws
sufficient to bring the temperature near the freezing point.
Let us now take a closer look at one of these preserved
mammoths, and see what it may have to tell us.
5. The Beresovka Mammoth
Perhaps the most famous individual mammoth found pre-
served in the permafrost was the so-called Beresovka mam-
moth. This mammoth was discovered sticking out of the
ground not far from the bank of the Beresovka River in
Siberia about 1901. Word of it reached the capital, St. Peters-
burg. It so happened that, a long time before, word of
another mammoth had come to the ears of Tsar Peter the
Great. With his strong interest in natural science, the Tsar
had issued a ukase ordering that whenever thereafter another
mammoth was discovered, an expedition should be sent out
by his Imperial Academy of Sciences to study it.
In accordance with this standing order, a group of dis-
THE GREAT EXTINCTIONS 245
tinguished academicians entrained at St. Petersburg and pro-
ceeded to the remote district of Siberia where the creature
had been reported. When they arrived they found that the
wolves had chewed off such parts of the mammoth as projected
aboveground, but most of the carcass was still intact. They
erected a structure over the body, and built fires so as to thaw
the ground and permit the removal of the remains. This
process was hardly agreeable, since, the moment the meat
began to thaw, the stench became terrific. However, several
academicians remarked that after a little exposure to the
stench, they became used to it. They ended by hardly notic-
ing it.
Eventually the body of the entire mammoth was removed
from the ground. The academicians, meantime, made careful
observations of its original position. They saw evidence that,
in their opinion, the mammoth had been mired in the mud.
It looked as if its last struggles had been to get out of the
mud, and as if it had frozen to death in a half-standing posi-
tion. Strangely enough, the animal's penis was fully erect.
Two major bones, a leg bone and the pelvic bone, had been
broken as if by a fall. There was still some food on the ani-
mal's tongue, and between his teeth, indicating an abrupt
interruption of his last meal. The preliminary conclusion sug-
gested by these facts was that the animal met his death by
falling into the river. A little later on we shall re-examine
this conclusion.
Very special interest attached to the analysis of the contents
of this animal's stomach. These consisted of about fifty
pounds of material, largely undigested and remarkably well
preserved. While the foregoing data were obtained from a
translation of parts of the report of the academicians, pub-
lished by the Smithsonian Institution, the section dealing
with the stomach contents was specially translated for this
work by my aunt, Mrs. Norman Hapgood. Since there are
many interesting points essential to an understanding of the
question, which can be noted only by a reading of the report
itself, and which do not figure in the published accounts, I
246 EARTH'S SHIFTING CRUST
reproduce the stomach analysis by V. N. Sukachev, with
omission of technical botanical terms where possible, and
with omission of bibliographical references to Russian, Ger-
man, and Latin sources, and some shortening of the com-
ment (410).
We can definitely establish the following types of plants in the
food in the stomach and among the teeth of the Beresovka mammoth
[Latin names are those of the Russian text]:
a. Alopecurus alpinus sin. The remains of this grass are numerous
in the contents of the stomach. A significant portion of it consists of
stems, with occasional remnants of leaves, usually mixed in with other
vegetable remains. ... All these remains are so little destroyed that
one is able to establish with exactitude to what species they be-
long. . . .
Measurements of the individual parts of these plants, when com-
pared with the varieties of the existing species, showed that the
variety contained in the food was more closely related to that now
found in the forest regions to the south of the tundra than to the
varieties now found in the tundra. Nevertheless, this is an Arctic
variety and is widely spread over the Arctic regions, in North America
and Eurasia. However, in the forested regions it runs far to the south.
b. Beckmannia eruciformis (L.) Host. The florets of this plant are
numerous in the contents of the stomach and usually are excellently
preserved. [The detailed description of the remains (with precise
measurements in millimeters) shows the species to be the same as that
of the present day, although a little smaller, which may be the result of
compaction in the stomach. At the present time the species is widely
prevalent in Siberia and in the Arctic generally. It grows in flooded
meadows or marshes. It is also found in North America, the south of
Europe, and a major part of European Russia (although it has not
been reported from northern Russia), almost all of Siberia, Japan,
North China, and Mongolia.]
c. Agropyrum cristatum (L.) Bess. Remains of this plant are very
numerous in the contents of the stomach. [They are so well preserved
that there is no doubt as to the exact species. The individual speci-
mens are slightly smaller than those of the typical more southern
variety growing today, but this could be the result of some reduction
of size because of pressure in the stomach, which is noted in other
cases.]
The finding of these plants is of very great interest. Not only are
they scarcely known anywhere in the Arctic regions, they are even, so
far as I have been able to discover, very rare also in the Yakutsk dis-
THE GREAT EXTINCTIONS 247
trict. . . . Generally speaking the Agropyrum cristatum L. Bess is a
plant of the plains (steppes) and is widespread in the plains of Dauria.
. . . The general range of this plant includes southern Europe (in
European Russia it is adapted to the plains belt), southern Siberia,
Turkestan, Djungaria, Tian-Shan, and Mongolia.
Nevertheless, the variety found in the stomach differs slightly from
both the European and Oriental-Siberian varieties found today.
d. Hordeum violaceum Boiss. et Huet. [After a detailed anatom-
ical description of the remains of this plant in the stomach contents,
the writer continues.] Our specimens are in no particular different
from the specimens of this species from the Yakutsk, Irkutsk, and
Transbaikal districts. [The plant is, apparently, no longer found
along the Lena River, except south of its junction with the Aldan
River. It is found in dry, grassy areas. It is not found in the Arctic
regions.] Its northernmost point is apparently Turochansk. . . . Gen-
erally speaking, in Siberia this plant is a meadow plant and is also
found in moister places in the plains.
e. Agrostis sp. ... it does not appear possible to identify the
species positively. [Apparently, no plant precisely similar is known at
the present day. Thus it may represent an extinct form.]
f. Gramina gen. et sp. A grass, but preservation is not good
enough to allow any more precise identification.
g. Carex lagopina Wahlenb. The remains of this sedge are numer-
ous in the contents of the stomach. [The specimens exactly resemble
varieties growing today. The measurements show no reduction in
size. Its range extends to the shores of the Arctic Ocean. It is found
in mountainous regions, including the Carpathians, Alps, and Pyre-
nees. It is also found in the peat bogs of western Prussia, in Siberia
as far south as Transbaikalia and Kamchatka, in eastern India, North
America, and the southern island of New Zealand.]
h. [Omitted— apparently a numbering error in the text.]
i. Ranunculus acris L. [The specimens in the stomach did not
permit identification of the precise variety of this buttercup, though
pods equally large are occasionally found.] The general range of this
plant is very great. It includes all Europe and Siberia, it stretches to
the extreme north, spreads to China, Japan, Mongolia, and North
America. However, over this area this species very much deteriorates
into many varieties which are considered by some to be independent
species. [This plant grows in rather dry places. It is not at present
found growing together with the Beckmannia Eruciformis, although
it is found with it in the stomach.]
j. Oxytropis sordida (Willd) Trantv. In the contents of the stom-
ach were found several fragments of these beans. ... In the frag-
248 EARTH'S SHIFTING CRUST
ments taken from the teeth there were found eight whole bean pods
in a very good state of preservation; they even in places retained five
beans. . . . [The plant is now found in Arctic and sub-Arctic regions,
but also in the northern forests. It grows in rather dry places.]
In addition to the nine species mentioned above, and de-
scribed in the report, with numerous measurements, the
author reports that two kinds of mosses were identified in
the stomach contents by Professor Broterus, of Finland.
There were five sprigs of Hypnum fluitans (Dill.) L. and one
sprig of Aulacomnium turgidum (Wahlenb.) Schwaegr. The
first is common in Siberia north of the Gist parallel of latitude
and to the marshlands of northern Europe. Both of them "be-
long to species widely distributed over both the wooded and
the tundra regions."
The report states, further, that another scientist, F. F. Herz,
brought back several fragments of woody substances and bark
from beneath the mammoth, and of the species of vegetation
among which it was lying. Very surprisingly, these were
found to differ in a marked degree from the contents of the
stomach. A larch (Larix sp.) was finally identified, but the
genus only, not the species.
Another tree identified in a general way was Betula Alba
L.S.I., but the exact species could not be determined. The
same was true of a third tree, Alnus sp. "All three of these
kinds grow at present in the Kolyma River basin, and along
the Beresovka, as they are widespread in general from the
northern limits of the wooded belt to the southern plains."
The general conclusions reached in the report are as
follows.
a. The remains of plants in the mammoth's mouth, among
its teeth, were the same as the stomach contents, and repre-
sented food the mammoth had not yet swallowed when it was
killed.
b. The food consisted preponderantly of grasses and sedge.
"No remains at all of conifers were found." Therefore, "one
may conclude that the Beresovka mammoth did not, as was
previously thought, feed mainly on coniferous vegetation but
THE GREAT EXTINCTIONS 24Q
mainly on meadow grasses." Evidently he wandered into
low, moist places, and also into higher, drier places such as
are now found in the same region.
c. "The finding of the wood remains under the mammoth,
and even the cliff itself where the mammoth was lying, sug-
gest that he was not feeding in the place where he died. The
majority of the vegetation in his food did not grow along
cliffs or in conjunction with species of trees."
d. The discovery of the ripe fruits of sedges, grasses, and
other plants suggests that "the mammoth died during the
second half of July or the beginning of August."
The report concludes that while the contents of the stom-
ach do not prove that the climate was warmer in the days of
the mammoth than it is today, neither do they exclude the
possibility that it was warmer. However, the climate was, in
any case, not much warmer. The evidence provides no clew
to the cause of the extinction of the mammoths.
6. The Interpretation of the Report
On the assumption that we are dealing with a displacement
of the earth's crust beginning about 18,000 years ago and
ending about 8,000 years ago, possibly punctuated by pauses
and renewals of movement, and by massive outbursts of vol-
canism that accounted for the repeated readvances of the ice
in North America, and by warm phases between these read-
vances, when the temperatures may have been warmed by
the increasing percentage of carbon dioxide in the air, we
may attempt to reconstruct the progression of events in
Siberia. This may furnish a basis for the interpretation of the
report, and of the other facts about the mammoths cited
above.
To begin with, if North America was moving gradually
southward during this period (along the goth meridian, as
we assume), then East Asia was moving northward along the
continuation of the same meridian, and it moved at the same
250 EARTH'S SHIFTING CRUST
rate, to the same distance, with the same pauses, if any. The
climate would be growing gradually colder, but with inter-
ruptions, for the colder and warmer phases caused in North
America by the volcanic dust and carbon dioxide (produced
by volcanic eruptions) would be universal; they would affect
the whole earth's surface in the same direction at the same
time. In Siberia, warm phases would check the deterioration
of the climate temporarily, while in North America the cold
phases would act to check its improvement. The total change
of climate in Siberia during this whole period would be very
great. Siberia would, at the beginning of the movement, have
been enjoying a warm temperate climate, warmer than that
of New York at the present time.
During the whole period, changes would gradually be tak-
ing place in the flora in eastern Siberia. Plants adapted to
wide ranges of climate, capable of surviving in the increasing
cold, would continue to grow in Siberia. It is interesting to
note in the foregoing report of the contents of the mam-
moth's stomach that every single plant or tree associated
with the time of the mammoth's death has a range extending
considerably to the south of that latitude today. Plants un-
able to survive in the increasing cold would retreat toward
the south, as two or three of the plants found in the stomach
evidently did. Arctic species and varieties would tend to in-
vade the region as the climate grew colder. The contents of
the mammoth's stomach would simply represent the mixture
of plants growing in Siberia during the particular part of the
period in which he lived. We learn from Runcorn that Soviet
scientists have dated a mammoth from the Taimir Peninsula,
considerably to the westward in Siberia, by radiocarbon, and
have found it to be about 12,300 years old (361). This means
that mammoths survived until toward the end of the crust
movement. The mammoth of the Beresovka may have lived
as late as or later than this, when the climate of Siberia had
deteriorated a great deal, though by no means to the present
level. The possibility exists that if we could find a mammoth
that had died during the earlier phase of the displacement
THE GREAT EXTINCTIONS 251
we would find a combination of plants in its stomach reflect-
ing a much warmer climate, but, of course, it is unlikely that
during that warmer period any mammoths would have been
preserved.
Just as we assume that North America subsided a thousand
feet or more relatively to sea level when the continent was
being moved equatorward, this being followed by a later
isostatic rebound of the crust, so we must logically assume a
progressive uplift of Siberia during its poleward displace-
ment, with subsidence since.
This uplift of Siberia, which I now suggest, is vitally im-
portant for the clarification of the facts relating to the mam-
moths. If we assume that, previous to the displacement, the
elevation of the lands in eastern Siberia and the Arctic was
about the same as now, we can see in this moderate uplift
(which is a necessary corollary of crust displacement) suffi-
cient added elevation to connect both the New Siberian
Islands with the Asiatic mainland, and Asia with North
America across the Behring Strait. Thus the migrations of the
animals to the New Siberian Islands and between Alaska and
Siberia are explained, without having to have recourse to
the theory of a sea level controlled by glacial melt water.
Then, the subsidence of the area by isostatic adjustment after
the end of the displacement (let us say, between 10,000 and
3,000 years ago) would have separated America, Asia, and the
New Siberian Islands, and it provides us with a clear and
sufficient explanation for the reported dredging up of mam-
moths' tusks from the bottom of the Arctic Ocean, or of their
being thrown up, as it is said, upon the beaches of the Arctic
Ocean during Arctic storms.
The progressive elevation of Siberia during the displace-
ment provides us, finally, with a very complete explanation
of the many curious, enigmatic circumstances surrounding
the discovery of the mammoths' remains, and those of other
animals. But before these problems can be explained, another
circumstance must first be briefly discussed.
I have mentioned that volcanic eruptions would be having
252 EARTH'S SHIFTING CRUST
their direct and indirect effects in Asia as in North America,
and, indeed, everywhere. The effect o£ volcanic dust, as we
have seen, is to chill the atmosphere. In the last chapter I
presented indirect evidence that the volcanism during the
displacement was at times massive enough to produce major
lowering of the average temperature, and continuous enough
to keep it low for long periods. In addition, I presented di-
rect evidence that many volcanoes were active during the
period in areas that are now quiet.
I can form no idea as to just how many volcanoes might
have been active simultaneously at any time during that dis-
placement of the crust. An educated guess is apparently not
possible. I will assume, however, that during any displace-
ment the average quantity of volcanism annually would be
considerably greater than at present. This seems a safe as-
sumption.
I will assume, secondly, that at intervals during the 10,000-
year period of the displacement, volcanism would reach a
higher point than the average for the whole period. This has
already been suggested (Chapter VII). Such periods would be
likely to occur while the crust was moving at its greatest speed,
that is, during the middle part of the period (Chapter XI).
These would be periods of readvance of the dwindling con-
tinental icecap. They would be of varying length, but some
of them would last a long time.
My third supposition will be that occasionally, during
periods of very active volcanism, there would occur a con-
junction of several major volcanic explosions in the same
year. The mathematical probabilities would favor this oc-
currence. It would be strange indeed, considering the stresses
and strains to which the crust of the earth would be sub-
jected during its displacement, if this did not happen now
and then.
Let us now look at the consequences of this. Let us sup-
pose five explosions in one year of the magnitude of the
explosion of Mt. Katmai (or a larger number of lesser ex-
plosions). According to Humphreys, this would produce
THE GREAT EXTINCTIONS 253
enough dust to intercept 100 per cent of the sun's radiation;
consequently, the earth's surface would receive no heat at all.
It seems very unlikely that things could ever have gone quite
as far as this; nevertheless, considering that volcanic dust is
circulated around the world in a matter of days, and that the
refrigerating effects on the atmosphere may be felt in a
matter of weeks or months, there exists the possibility of a
sudden and drastic fall in temperature following soon after
such a conjunction of volcanic explosions.
The direct effects of this sudden fall in temperature on
animals would be serious enough, but the indirect effects
concern us more, for the moment. The amount of humidity
the atmosphere can hold is proportional to temperature. If
a mass of air is heated, it will pick up more moisture. If it is
cooled drastically, the precipitation will be drastic, in the
form of either rain or snow. At the same time, precipitation
will be increased by an increase in the number of dust par-
ticles in the air, because raindrops require dust particles to
condense around, or so it is thought. Our situation, after a
massive outburst of volcanism in a short period, would be
that while the air was being drastically cooled, there would
at the same time be an enormous increase of the convenient
dust particles. This could add up to precipitation of moisture
on an enormous scale.
Now let us return to Siberia. Let us suppose that the
region is being steadily moved northward, and that its eleva-
tion above sea level is increasing. In a certain year, a conjunc-
tion of several major volcanic eruptions takes place. Let us
come back to our Beresovka mammoth. He is feeding quietly
in the grassy meadow, and he has just swallowed a mouthful
of buttercups, and has gathered up, with his trunk, a new
mouthful of wild beans, The temperature is warm, and
there is no sign of what is about to occur. The volcanoes have
shot off their dust some time before. Cold air* currents are
circulating ominously, but unperceived, not far away.
I have seen a situation like this in Canada, during Indian
summer. Day after day the sun is warm, although the nights
254 EARTH'S SHIFTING CRUST
are cold. The forest still has a summer look. It is still possible
to swim in the lake, and then come out and stretch in the sun
to get dry and warm. But suddenly, without transition, in
the course of a few hours, the northwest wind brings winter.
The lake freezes up, and the very next day, as far as the eye
can see, there is nothing but ice and snow.
Things moved faster, or at least more drastically, in the
grassy meadow. The storm came down early in August, per-
haps first with rain, and terrific wind. Humphreys has
pointed out that the effect of a large quantity of volcanic
dust in the atmosphere must be to increase the temperature
gradient between the poles and the equator, resulting in
more rapid circulation of the air, in winds of greater velocity.
I shall present additional evidence of this in the following
pages. Since winds occasionally attain a velocity of 150 miles
an hour or more even today, we may conservatively suppose
that the storm could have hit the grassy meadow at that
speed. At the beginning of the disturbance, the mammoth
would have stopped eating—without even bothering to swal-
low the last few beans in his mouth. He would have left the
meadow and, accompanied by his friends, sought shelter in
the nearest forest, as, no doubt, he had often done before
during storms. Here, in the confusion of the storm, perhaps
because of the force of the wind itself, he may have fallen
over the cliff at the bottom of which his body was found. He
was not killed, but a leg bone and his pelvic bone were
broken. He couldn't walk, so he lay there, while the wild
hurricane in a very few hours brought down subzero air
masses from the polar zone, and the rain turned to snow, and
piled up around him. He lifted the fore part of his body as
far as he could above the snow, but it piled up, in the lee of
the cliff over which he had fallen, until it was above his head.
By this time, however, he might already have frozen to death
in his half-standing posture. A similar fate would have en-
gulfed millions of animals. During the ensuing months of
winter the snow mantle would still thicken, and during the
THE GREAT EXTINCTIONS 255
following summer, because of the continuing effects of the
volcanic dust, it would scarcely melt at all.
At this point many animals have been frozen into the
snowdrifts; moreover, except for some that may have been
dismembered by the force of the wind, they are intact. They
are frozen in the ice of a nascent icecap. Since the region
moves ever northward, the ice cover tends to remain over
most of the area; it does not quite melt away during the
summers, and it gets thicker and thicker as Siberia ap-
proaches the pole.
But here some impatient reader with some geological
knowledge will break in and say, "But there was no icecap
in Siberia! " Quite so: no continental icecap finally devel-
oped; the icecap that began to grow never came to maturity.
Instead, it melted away.
One need not look far for the explanation of this. We have
noted that the region was uplifted during the displacement.
In the earlier stages, while the climate was still warm, the
uplift had been sufficient to open land communications with
the New Siberian Islands and Alaska. In climate, a slight in-
crease of elevation may be the equivalent of hundreds of
miles of latitude. So, after a movement of the crust had pro-
gressed to a certain distance, and the resulting increased
elevation of the land had brought lowered temperatures, a
thin icecap stretched over northern Siberia.
But when, after the end of the displacement, isostatic ad-
justment began to correct the elevation, and to bring the
area down, it also warmed the climate, and so the nascent
icecap melted away, and no doubt this development was
furthered by the Climatic Optimum. During this warm pe-
riod, the ice sheet in Siberia may have melted very rapidly,
and torrents of melt water may have borne the bodies of
the animals along, after they were disengaged from the ice,
and torn their bodies apart, and heaped them up in great
numbers as we find them, and buried them in vast seas of
freezing mud. In most cases, of course, only the bones re-
mained. Brooks cites a statement by Flint and Dorsey (160:
256 EARTH'S SHIFTING CRUST
627) giving evidence of a recent "thin and inactive" ice
sheet in Siberia, exactly as the hypothesis demands.
It might frequently occur that an animal would escape
being washed out of the melting icecap. It would seem that
the Beresovka mammoth was one of these. He seems to have
remained frozen in the attitude of his last struggle in the
snowdrift. In a succession of thaws, however, the ice encasing
his body was apparently washed away and replaced by freez-
ing mud. The temperature of the carcass may have ap-
proached the melting point at these times, but though this
would have destroyed the edibility of the meat, it would not
have disintegrated the body. It would even have been pos-
sible for the outside of the body to have thawed briefly
during its translation from the icecap to the permafrost with
little or no decay, because of the absence of germs in the
Arctic climate. It would seem that the Academicians who
examined the mammoth in situ were not impressed with
his edibility; they did not try any mammoth steaks.
It appears that this assumption of a thin, temporary ice-
cap in Siberia gradually transformed into permafrost solves
most of the outstanding questions about the mammoths and
the other animals whose remains are found in Siberia. It ex-
plains, for example, why some of the mammoths have been
found on the highest points of the tundra. It explains the
configuration of the deposits in which they are found. It
explains Tolmachev's remark that "mammoth-bearing drift
deposits sometimes have a thickness of tens of feet, sometimes
they are spread out in comparatively thin layers" (422:51).
The "drift deposits" are water-formed; they can now be ex-
plained as the result of the melting of the thin icecap, which
must have produced rapidly flowing rivers that picked up
and deposited quantities of mud, thicker in some places than
in others, and filled with bodies and parts of bodies dropped
out of the icecap. The prompt refreezing of these seas of
mud, after the thaw, created the permafrost.
But even if these assumptions seem to solve the problems,
the reader may still say, "Well—very good. But what if all
THE GREAT EXTINCTIONS 257
this isn't true after all?" All I can then do is to point to
some tangible evidence that exactly this sort of thing hap-
pened in another part of the earth. But to examine this evi-
dence we must turn aside into one of the byways of science,
and examine an unsuspected facet of the Wisconsin glacia-
tion. We must return to North America, and reconstruct the
story of the birth of that icecap.
7. The Mastodons of New York
About seventy-five years ago, considerable excitement was
aroused in scientific and popular circles by the discovery of
the remains of extinct animals in various parts of the United
States. Perhaps the most sensational of these finds was that
of the mastodons. Many of these were found in New York
State, and in some cases they were so well preserved that it
was still possible to analyze the contents of the animals'
stomachs. Some extensive accounts of these mastodons have
appeared in print (178, 309, 203). Since science, like clothing,
has its fashions, a period of attention to the mastodons was
followed by a period of neglect. Neglect did not overtake
them, however, before conclusions were reached respecting
them. It was noted that nearly all the best-preserved remains
were found in bogs and swamps, where, it was assumed, they
had been mired and sucked down to their deaths.
This explanation of their deaths was accepted, apparently
without any dissent, and it involved, of course, the acceptance
also of the opinion that the animals had inhabited New York
State after the departure of the ice sheet. It was concluded
that the animals were postglacial. The conclusion was inevi-
table, because the ice sheet would have plowed up all bogs,
and the animals' bodies could not have been preserved from
destruction by it.
So the matter rested— the mastodons ceased to attract at-
tention. There followed a period during which the general
trend of scientific opinion led finally to the view that neither
258 EARTH'S SHIFTING CRUST
mammoths nor mastodons, nor any of the other extinct Pleis-
tocene animals, had lived in North America after the ice age.
But no one has gone back to dig up the evidence of the mas-
todons and ask how, if they did not live in New York State
after the ice age, they came to be buried in the bogs where
they are found. It is now our task to reopen this closed chap-
ter, to drag these ancient beasts once more from their tomb.
We shall first look at some of their case histories, and then
summarize our findings.
One might imagine two alternative solutions of the prob-
lem. Either the mastodons lived in New York State after the
ice age, and got themselves mired in the bogs where their
bodies are found, or they got mired in the bogs before the ice
age, and somehow escaped destruction by the passage over
them of the mile-thick ice sheet. In the latter case, the ani-
mals would have been found in beds of swampy vegetable
stuff below the sand, gravel, and striated stones deposited by
the glacier. How, then, are we to explain the fact that the
animal remains are not found in this layer but are mixed
up with the glacial materials themselves? Since this is usually
true, we are driven to the conclusion that the animals were
mired in New York State bogs neither before nor after the
coming of the ice sheet. Before pressing on to further con-
clusions, let us consider the details of a few cases.
In August, 1871, a mastodon was discovered one mile
north of Jamestown, New York, and the remains were ex-
amined in situ by Professor S. G. Love and others. Love de-
scribed the find as follows:
On the east side of the Fredonia road, about one mile north of
Jamestown, is the farm of Joel L. Hoyt. About 500 yards from the
road is a sink or slough covering about an acre, possibly more in ex-
tent, and varying from two to eight feet in depth, and fed by several
living springs. Cattle have been mired and lost there since the farm
was first occupied. Mr. Hoyt drained the sink and left the muck to
dry, and later commenced an excavation there. The work of excava-
tion had continued a little more than a week, when the workmen
began to find (as they supposed) a peculiar kind of wood and roots,
THE GREAT EXTINCTIONS 259
imbedded some six feet beneath the surface. For several days they
continued to carry the small pieces into an adjoining field with the
muck, and to pile the larger ones with pine roots and stumps to be
burned. But Mr. Hoyt discovered unmistakable evidences of the re-
mains of some huge animal. At once there was a change in the pro-
cedure, in order to secure specimens and determine their character.
It was difficult to determine the precise position of the remains, as
they were much disturbed and partially removed before any special
notice was taken of them. From the best information I could get, I
conclude that the body lay with the head to the east, from four to six
feet beneath the surface, and in a partially natural position. Many
of the bones were, however, out of place. The lower jaw was about
five feet from the head and lay on the side crushed together so that
the rows of teeth were very near each other. The tusks extended
easterly in nearly a natural position, and, judging from the statements
of Mr. Hoyt and the workmen, they must have been from ten to
twelve feet in length. After digging into the gravel and clay about
ten inches I found traces of a rib, decayed but distinctly marked,
over five feet in length. Where the body must have lain were found
large quantities of vegetable matter (evidently the contents of the
stomach) mostly decayed, in which were innumerable small twigs
varying from one half inch to two inches in length. The remains were
all in a very forward state of decay; and when I reached the ground
I found it possible to do little more than had already been done to
preserve them. . . . (203:14-15). [There follows a list of individual
parts found.]
Here an important point is the fact that parts of the re-
mains were found mixed with the sand and gravel, which
had been deposited by the ice sheet as it retreated. This fact
suggests that the carcass may have been dropped or washed
out of the icecap into a glacial pool, which later through a
process of countless freezings and thawings and accumula-
tion of sediments became a bog. Later Professor Love am-
plified the foregoing remarks in a very interesting manner,
in a paper read before the Chautauqua Society of History
and Natural Science, July 16, 1885:
The twigs found in such large quantities where the stomach would
naturally be were found, upon microscopical examination and com-
parison, to be of the same kind (genera and species) as the cone bear-
ing trees (pine and spruce) of the present day. Mingled with the twigs
260 EARTH'S SHIFTING CRUST
was a mass of yellowish fetid matter, probably the remains of some
vegetation which did not possess the staying qualities of the balsamic
cone-bearers (203:15-16).
Several important points are illustrated in these passages.
They are all brought out, as well, in numerous other cases.
The more significant points appear to be:
a. The rib was found buried in the glacial material under
the muck, as already mentioned.
b. Some force crushed the jaw and separated other parts of
the body, without completely disturbing its natural position.
We shall find many cases of this sort of thing.
c. The stomach was found to contain evidence of vegeta-
tion such as now grows in New York State. Since the animal
did not live after glacial times, and since the vegetation
naturally did not exist in New York State when it was cov-
ered by a mile of ice, it follows that the animal lived in the
last Interglacial Period, and that New York then had a cli-
mate something like the present.
d. The discovery of the remains in a mire tells us nothing
of the mode of death, because only in a mire would they
have had any chance of being preserved. Animals dying in
other situations, or left in dry places by the retreating ice,
would have disintegrated completely.
e. The evidence favors the conclusion that the body of
the mastodon was preserved within the vast ice sheet itself,
and was deposited when the ice withdrew, in a bog where
conditions continued to favor its preservation. The power of
bogs to preserve animal and vegetable matter for long pe-
riods is well known.
The instances cited by Hartnagel and Bishop of mastodons
that clearly were not mired in bogs include one mastodon
whose remains, a tusk, were found in sand near Fairport;
another whose tusk and teeth were found in sand and gravel
in the town of Perrinton; one whose remains (ribs, skull,
tusk, leg bone) were found "about four feet below the sur-
face in a hollow or water course, lying on and in a very hard
body of blue clay, and about two feet above the polished
THE GREAT EXTINCTIONS g6l
limestone . . ."; "a rib of a mammoth or mastodon found
12 feet below the surface of the ground in gravel" at Roches-
ter, and other instances (203:35-39).
Dr. Roy L. Moodie, of the New York State Museum, in
his Popular Guide to the Nature and the Environment of the
Fossil Vertebrates of New York, discusses a mastodon that
was deposited entire in a glacial pothole:
. . . The pothole was made by whirling waters grinding the loose
stones in a depression, gradually deepening in the post-glacial Mo-
hawk River, and the body of the mammoth carne down with the ice
and dropped into the hole. . . . (309:103-05).
This particular case provides an excellent illustration of the
process by which so many of the animal bodies were torn
apart, not only in New York State but also probably in Si-
beria, where the melting of a thinner ice sheet would still
have produced torrents in which the bodies detached from
the ice could be dashed against rocks and broken to pieces.
Hartnagel and Bishop, referring to the few remains of
mammoths that have been found in New York State, remark:
There is no doubt that the mammoth remains were imbedded in
the sand and gravels laid down during the recession of the ice sheet.
Examples of these are best seen in the Lewiston specimens of teeth
and bones which were found deeply buried in the spit formed in Lake
Iroquois. . . . (203:67).
Sir Charles Lyell visited the site of the discovery of a mas-
todon near Geneseo, Livingston County, New York, and
described his observations in his Travels in North America^
in a passage quoted by Hartnagel and Bishop:
I was desirous of knowing whether any shells accompanied the
bones, and whether they were of recent species. Mr. Hall and I there-
fore procured workmen, who were soon joined by some amateurs o£
Geneseo, and a pit was dug to a depth of about five feet from the
surface. Here we came upon a bed of white shell marl and sand, in
which lay portions of the skull, ivory tusk and vertebrae, of the ex-
tinct quadruped. The shells proved to be all of existing freshwater
and land species now common to this district. I had been told that
the mastodon's teeth were taken out of muck, or the black superficial
262 EARTH'S SHIFTING CRUST
peaty earth of the bog. I was therefore glad to ascertain that it was
really buried in the shell-marl below the peat, and therefore agreed
in situation with the large fossil elks of Ireland, which, though often
said to occur in peat, are in fact met with in subjacent beds of marl
(203:31-32).
Let us, in passing, note in this passage the evidence that
whatever occurred in Siberia and in North America (though
perhaps at different times) seems also to have occurred in
Ireland.
If it is now clear that the mastodons were actually con-
tained in the great continental glacier, a question may arise
as to their probable numbers. Were these animals rare or did
they exist in great herds? Hartnagel and Bishop quote an
earlier writer, who remarked:
... I have been particular in stating the relative situations and
distances of those places in which bones have been discovered, from
a certain point, to show, from the small district in which many dis-
coveries have been made, the great probability that these animals
must have been very numerous in this part of the country, for if we
compare the small proportion that swamps, in which only they are
found, bear to the rest of the surface, and the very small proportion
that those parts of such swamps as have yet been explored, bear to
the whole of such swamps, the probable conclusion is that they must
once have existed here in great numbers (203:62).
It must not be supposed that only mastodons and some
mammoths were thus caught in the ice sheet and deposited
as it retreated. Hartnagel and Bishop give instances of the
finding of remains of foxes, horses, large bears, black bears,
giant beaver, small beaver, peccaries, deer, elk, caribou,
moose, and bison, forming a mixture of extinct and still
living species, all deposited in the same way (203:81-94).
Moreover, discoveries were not confined to New York State,
but embraced the entire area once covered by the great ice
sheet
We must therefore conclude that in all probability some
millions of all these sorts of animals were enclosed in the ice
sheet. Now the question must be asked, Did they live in the
regions where they are now found, or were they carried
THE GREAT EXTINCTIONS 263
greater or lesser distances by the moving ice? This is an im-
portant question. Glaciers often carry vast quantities of de-
bris, even huge boulders, hundreds of miles, even in some
cases uphill (63:14-15). Hartnagel and Bishop give an ex-
cellent description of the way in which a great ice sheet
moves, and provide a partial answer to the question, in the
following passage:
The remains of most of the Canadian animals that were over-
whelmed in and by the glacial snows were incorporated in the lower,
or ground-contact ice of the southward moving sector of the Quebec
(Labradorian) ice cap. The deepest portion of the ice cap was pushed
into the deep Ontarian valley and becoming stagnant because of its
position and also because of its load of detritus, it served during all
the duration of the Quebec glacier as a bridge over which the upper
ice, by a shearing flow, passed on south over New York. This element
of glacier mechanics is fundamental to the present explanation of the
peculiar distribution of the Elephas remains and is believed to de-
scribe the behavior of the continental glacier toward deep and
capacious valleys, not only those transverse to the ice flow but also
longitudinal valleys. . . . (203:69).
This statement should be supplemented by Coleman's re-
mark that a great continental icecap, independently of any
valleys, moves only in its upper layers, except at the edges.
The layers near the ground are stagnant. This is the reason,
he says, that the evidences of glaciation are found mostly on
the exterior fringes of the area once occupied by the ice
sheet. The central areas escape the grinding and plowing
up that leave such evidences in the latter areas.
The usual explanation of this remarkable fact leaves some-
thing to be desired. According to the accepted concept, an
ice sheet forms first in a small area, and then spreads out,
presumably after it has become thick enough to move out-
ward by the force of gravity. That means, it seems to me,
that all but a small central area should show signs of having
been passed over by the glacier. Yet, according to Coleman,
the opposite is the case.
I think our assumption provides a good answer to this
problem, for the initial snows, such as we assume may have
264 EARTH'S SHIFTING CRUST
occurred in Siberia as the result of dust produced by massive
outbreaks of volcanism, would cover a considerable area,
enclosing the animal remains. Later, if the ice sheet de-
veloped enough to move by gravity, the upper layers would
move, leaving a stagnant layer, at least in some places, to pro-
tect the animals, and only at the remote fringe or at high
points of the area would the now moving icecap containing
its load of rocks and pebbles be continuously in contact with
the ground. In Siberia the icecap, if there was one, never
grew thick enough to move by gravity. In North America,
on the other hand (at an earlier time), the icecap did grow,
until it began to move.
So we may conclude that the animals contained in the
great North American icecap were mostly living, at the time
they were overwhelmed by the snow, in the places where
they are now found. It would not be wise, of course, to ex-
clude entirely the transportation of animal remains in the
ice sheet; very certainly it occurred, and perhaps quite often,
but in all probability the vast majority of the animals were
in the stagnant ground-contact ice. We have seen that the
animals represented in the collection in the glacier indicate
a temperate climate, like that prevailing in New York State
today. Now the final question is, How did these millions of
animals, living in a temperate zone, get caught in the ice
sheet?
Note that here there is no dispute about the climate at
the time the animals were living. Here the situation is free
from the uncertainty surrounding the exact climate in which
the Beresovka mammoth lived. The animals listed above are
sufficient in themselves to establish the fact of a temperate
climate; however, there is an additional piece of evidence,
in the form of a quite fascinating botanical analysis of the
contents of a mastodon's stomach. Hartnagel and Bishop
quote from a report by Dr. J. C. Hunt:
The remains, both of cryptogams and flowering species, were in
abundance. Stems and leaves of mosses were wonderfully distinct in
structure, so much so that I could draw every cell. I even readily de-
THE GREAT EXTINCTIONS 265
tected confervoid filaments, with cells arranged in linear series, re-
sembling species now found in our waters. Numerous black bodies,
probably spores of the mosses, were found in abundance. Not a frag-
ment of sphagnum was seen in the deposit. I found, however, one
fragment of a water plant, possibly a rush, an inch long, every cell
of which was as distinct as though growing but yesterday. Pieces of
the woody tissue and bark of herbaceous plants, spiral vessels, etc.,
were abundant. Carapaces of Entomostraca were present, but no trace
of coniferous plants could be detected. It hence appears that the
animal ate his last meal from the tender mosses and boughs of flower-
ing plants growing on the banks of the streams and margins of the
swamps, rather than fed on submerged plants; and it is probable,
moreover, that the pines and cedars, and their allies, formed no part
of the mastodon's diet (203:58).
Here we see that everything indicates a climate similar to
that of New York today. An interesting point is the differ-
ence between the mastodon's diet indicated here and that
indicated in the case mentioned earlier. Speculation suggests
that perhaps the diet in this second case indicates the ani-
mal's preferred diet, or perhaps merely the diet available in
the summer, while that in the earlier case, in which twigs
were so important, may represent either the winter diet of
the mastodon or an emergency diet, the result of the de-
struction of the normal diet by the events occurring just be-
fore the animal's death. In any case, the second diet indicates
that whatever happened to that mastodon certainly took
place in the summer.
Now it is obvious that the arguments used to explain away
the evidence of climatic change in Siberia won't work in New
York. Here there was certainly climatic change, with a venge-
ance. The explanation I have offered for the preservation
of the Siberian remains will cover both cases. The great dif-
ference between them, aside from the failure of the Siberian
ice sheet to develop into a real icecap, consists of the fact that
while the melting of the thin Siberian ice sheet left a perma-
frost in which many remains could be preserved, the melting
of the Wisconsin icecap left temperate conditions in which
nothing could be preserved except what happened to find
sj66 EARTH'S SHIFTING CRUST
itself in bogs. Thus the great accumulations of bodies, such
as are found in Siberia, and such as probably also were piled
up by the rushing torrents coming from the melting Wis-
consin icecap, simply rotted away and left not a trace behind.
Now that we have satisfactorily established that the masto-
dons were imprisoned in the Wisconsin icecap itself, it is
necessary to add the correction that, despite this, they also
survived the ice age, at least in western North America.
Radiocarbon dates from 9,600 to 5,300 years ago have been
found for some mastodon remains. It must be conceded that
they may possibly have survived in North America until a
much later date than this. They therefore could have lived
in New York State after the ice age and have been caught in
bogs. But they must also have lived in New York State before
the ice age and been caught in the icecap, for otherwise their
remains would not have been found in so many cases inter-
mixed with the glacial materials (434).
8. Storm!
I have referred to the possibility that the extinction of ani-
mals and preservation of their bodies may be accounted for
in part by violent atmospheric disturbances, and I have of-
fered some evidence that such disturbances did accompany
the last displacement of the crust, and therefore, presum-
ably, earlier displacements.
It may be hard to distinguish between the effects on ani-
mal life of ice action (that is, of being melted out of glaciers
and subjected to the action of glacial streams) and the effects
of atmospheric factors. Nevertheless, perhaps some evidence
of the operation of the atmospheric factors is available.
The evidence is presented, in part, by Professor Frank C.
Hibben, in The Lost Americans, and since his description of
the evidence is firsthand, and is presented so clearly, I have
asked his permission to reproduce the pertinent passages.
He begins with a general description of the Alaskan muck,
THE GREAT EXTINCTIONS 267
in which enormous quantities of bones (and even parts of
bodies) are found:
In many places the Alaskan muck is packed with animal bones and
debris in trainload lots. Bones of mammoth, mastodon, several kinds
of bison, horses, wolves, bears, and lions tell a story of a f aunal popu-
lation. . . .
The Alaskan muck is like a fine, dark gray sand. . . . Within this
mass, frozen solid, lie the twisted parts of animals and trees inter-
mingled with lenses of ice and layers of peat and mosses. It looks as
though in the midst of some cataclysmic catastrophe of ten thousand
years ago the whole Alaskan world of living animals and plants was
suddenly frozen in midmotion in a grim charade. . . .
Throughout the Yukon and its tributaries, the gnawing currents
of the river had eaten into many a frozen bank of muck to reveal
bones and tusks of these animals protruding at all levels. Whole
gravel bars in the muddy river were formed of the jumbled fragments
of animal remains. . . . (212:90-92).
In a later chapter Professor Hibben writes:
The Pleistocene period ended in death. This is no ordinary extinc-
tion of a vague geological period which fizzled to an uncertain end.
This death was catastrophic and all-inclusive. . . . The large animals
that had given their name to the period became extinct. Their death
marked the end of an era.
But how did they die? What caused the extinction of forty million
animals? This mystery forms one of the oldest detective stories in the
world. A good detective story involves humans and death. These
conditions are met at the end of the Pleistocene. In this particular
case, the death was of such colossal proportions as to be staggering to
contemplate. . . .
The "corpus delicti" of the deceased in this mystery may be found
almost everywhere ... the animals of the period wandered into
every corner of the New World not actually covered by the ice sheets.
Their bones lie bleaching on the sands of Florida and in the gravels
of New Jersey. They weather out of the dry terraces of Texas and
protrude from the sticky ooze of the tar pits of Wiltshire Boulevard
in Los Angeles. Thousands of these remains have been encountered
in Mexico and even in South America. The bodies lie as articulated
skeletons revealed by dust storms, or as isolated bones and fragments
in ditches or canals. The bodies of the victims are everywhere in evi-
dence.
It might at first appear that many of these great animals died
268 EARTH'S SHIFTING CRUST
natural deaths; that is, that the remains that we find in the Pleistocene
strata over the continent represent the normal death that ends the
ordinary life cycle. However, where we can study these animals in
some detail, such as in the great bone pits of Nebraska, we find liter-
ally thousands of these remains together. The young lie with the old,
foal with dam and calf with cow. Whole herds of animals were appar-
ently killed together, overcome by some common power.
We have already seen that the muck pits of Alaska are filled with
the evidences of universal death. Mingled in these frozen masses are
the remains of many thousands of animals killed in their prime. The
best evidence we could have that this Pleistocene death was not sim-
ply a case of the bison and the mammoth dying after their normal
span of years is found in the Alaskan muck. In this dark gray frozen
stuff is preserved, quite commonly, fragments of ligaments, skin, hair,
and even flesh. We have gained from the muck pits of the Yukon
Valley a picture of quick extinction. The evidences of violence there
are as obvious as in the horror camps of Germany. Such piles of
bodies of animals or men simply do not occur by any ordinary natural
means. . . . (212:168-70).
So far, Professor Hibben's description of the evidence in
Alaska may be consistent with the solution I have suggested
for the evidence in Siberia, and for the area of the former
Wisconsin icecap. No doubt Alaska also had a temporary
icecap, since it was, in effect, merely an extension of Siberia,
and apparently had the same kinds of animals at about the
same time. However, it is evident that the animals that were
killed far to the south, in Florida, Texas, Mexico, and
South America, cannot have been contained in any icecap,
whether thin or thick. Professor Hibben suggests that other
factors were at work.
One of the most interesting of the theories of the Pleistocene end
is that which explains this ancient tragedy by world-wide, earth-
shaking volcanic eruptions of catastrophic violence. This bizarre idea,
queerly enough, has considerable support, especially in the Alaskan
and Siberian regions. Interspersed in the muck depths and sometimes
through the very piles of bones .and tusks themselves are layers of
volcanic ash. There is no doubt that coincidental with the end of the
Pleistocene animals, at least in Alaska, there were volcanic eruptions
of tremendous proportions. It stands to reason that animals whose
flesh is still preserved must have been killed and buried quickly to
THE GREAT EXTINCTIONS 269
be preserved at all. Bodies that die and lie on the surface soon dis-
integrate and the bones are scattered. A volcanic eruption would ex-
plain the end of the Alaskan animals all at one time, and in a manner
that would satisfy the evidences there as we know them. The herds
would be killed in their tracks either by the blanket of volcanic ash
covering them and causing death by heat or suffocation, or, indirectly,
by volcanic gases. Toxic clouds of gas from volcanic upheavals could
well cause death on a gigantic scale. . . .
Throughout the Alaskan mucks, too, there is evidence of atmos-
pheric disturbances of unparalleled violence. Mammoth and bison
alike were torn and twisted as though by a cosmic hand in Godly
rage. In one place, we can find the foreleg and shoulder of a mam-
moth with portions of the flesh and the toenails and the hair still
clinging to the blackened bones. Close by is the neck and skull of a
bison with the vertebrae clinging together with tendons and liga-
ments and the chitinous covering of the horns intact. There is no
mark of a knife or cutting instrument. The animals were simply torn
apart and scattered over the landscape like things of straw and string,
even though some of them weighed several tons. Mixed with the piles
of bones are trees, also twisted and torn and piled in tangled groups;
and the whole is covered with fine sifting muck, then frozen solid.
Storms, too, accompany volcanic disturbances of the proportions
indicated here. Differences in temperature and the influence of the
cubic miles of ash and pumice thrown into the air by eruptions of
this sort might well produce winds and blasts of inconceivable vio-
lence. If this is the explanation of the end of all this animal life, the
Pleistocene period was terminated by a very exciting time indeed
(212:176-78).
In Chapters IV and VII we saw that volcanic eruptions,
possibly on a great scale, are a corollary of any displacement
of the crust; therefore, our theory strongly supports and re-
inforces the suggestions advanced by Professor Hibben, and
at the same time his evidence strongly supports our theory.
But Professor Hibben points out certain consequences that
would flow from our theory, which I have not stressed. Wher-
ever volcanism is very intensive, toxic gases could locally be
very effective in destroying life. This is also true of violent
local windstorms. Massive volcanic eruptions might, of
course, occur anywhere on earth during a movement of the
crust, and we saw, in Chapter VII, that they apparently oc-
270 EARTH'S SHIFTING CRUST
curred in a good many places, some of them far removed
from the ice sheets themselves.
Despite the unquestionable importance of these locally
acting factors, it seems that we must give much greater im-
portance to the meteorological results of the universally act-
ing volcanic dust. As we have noted, this dust has a powerful
effect in reducing the average temperatures of the earth's
surface. A sufficient fall in temperature could easily wipe out
large numbers of animals, either directly, or by killing their
food, or even by favoring the spread of epidemic diseases.
Then, the dust could greatly increase rainfall, which, in cer-
tain circumstances, would produce extensive floods, thus
drowning numbers of animals and perhaps piling their bod-
ies in certain spots. As already mentioned, the dust would
also act to increase the temperature differences between the
climatic zones (the temperature gradient), thereby increasing,
perhaps very noticeably, the average wind velocities every-
where. Violent gales, lasting for days at a time, and recurring
frequently throughout the year, might raise great dust storms,
in which animals might be caught and killed by thirst or suf-
focation. It must not be forgotten that, at the same time,
changes in land elevations would be in progress, and these
also would be affecting the climate and the availability of
food supplies. The gradual character of these changes would
be punctuated, at times, by the abrupt release of accumulat-
ing tensions in the crust, accompanied by terrific earthquakes
and by sudden changes of elevation locally amounting per-
haps to a good many feet, which also could be the cause of
floods either inland (by the sudden damming of rivers) or
along the coasts. There is, as a matter of fact, as already
mentioned, much evidence of turbulence throughout the
world, during the last North American ice age, not only in
the air but in the sea.
I have not been able to make a complete survey of this evi-
dence. Nevertheless, a few additional items have come to my
attention. Ericson, for example, finds that turbidity currents
in the sea were more powerful during the ice age than they
THE GREAT EXTINCTIONS 271
are today (141:217). Kulp found, by radiocarbon dating, that
deposition of sediments along the eastern coast of North
America occurred at a fast rate prior to about 15,000 years
ago (262). Millis cited evidence of very violent winds during
the melting phase of the Wisconsin icecap (308:14). Violent
storms would seem a very natural explanation for the pe-
culiar finds of many bodies of animals crammed into caverns
and fissures, dating from various geological periods, that
have been found in various parts of the world. Hibben men-
tions one of these (212:173-74). It would seem possible that,
in storms of the character that may have occurred, caverns
may have been the only refuges available for man and beast
alike. Dodson refers to the fact that the destruction of ani-
mals in dust storms was apparently the cause of the preserva-
tion of many fossils (115:77). Volchok and Kulp, in their ex-
amination of ionium dating as applied to several Atlantic
Ocean deep-sea cores, remarked that "at the close of the Wis-
consin [glacial period] the rates of sedimentation for both
sediment types [red clay and Globigerina ooze] increased by
factors of 2-4" (442a:2ig). This means that the rate of dep-
osition of sediment in the deep sea at these points was in-
creased by from 200 to 400 per cent. This certainly suggests
an unusual turbulence for the climate.
It is little wonder that, faced by all these unpleasant con-
ditions, a good many species in all parts of the world, even
very far from the icecaps, gave up the struggle for existence.
In conclusion, it appears to me that the whole mass of the
evidence relative to the animal and plant remains in the
Siberian tundra, interpreted in the light of the evidence
from North America, sufficiently confirms the conclusion
that there was a northward displacement of Siberia coinci-
dent with the southward displacement of North America
at the end of the
IX : EARLIER DISPLACEMENTS
OF THE CRUST
/. Introduction
According to the evidence presented in the last two chapters,
the Hudson Bay region lay at the North Pole during the
period of the Wisconsin ice sheet. It is not possible (with
evidence now at hand) to define the geographical position
of the pole more exactly; it may have been located in Hudson
Bay itself, somewhat to the west in Keewatin, or somewhat to
the east in the province of Quebec. Coleman refers to the
fact that the earlier advance of the Wisconsin ice sheet en-
tered Michigan from the north— from the direction of Hud-
son Bay— rather than from Labrador (87:16). Flint remarks:
... It is evident that in Gary time, the ice first entered Minnesota
from the Rainy Lake District on the north, later from the northwest,
and still later from the northeast via the Lake Superior basin. . . .
Flint explains that all the known centers of the Wisconsin
glaciation are relatively late; they date from the declining
stage, when, according to our theory, the crust was in mo-
tion. The evidence of the earlier centers would, he points
out, have been destroyed by the ice flow of later times (375:
171). It is evident that the two principal ice sheets in this re-
gion—the so-called Keewatin and Labradorean ice sheets-
were part of the same glaciation, and were contemporary,
although the western center was the first to develop. Coleman
mentions that this earlier phase of the ice sheet— the so-called
Keewatin— transported boulders from the Laurentian area
near Hudson Bay to the foothills of southern Alberta, depos-
iting them at an altitude of 4,500 feet (87:15). This would
indicate that the ice was moving westward from Hudson Bay.
EARLIER DISPLACEMENTS OF CRUST 273
It would also indicate that the ice sheet at this time was
about a mile thick, while the Labrador ice sheet, at least
in its later phases, was not nearly so thick (375:169). The
suggestion here is strong that the pole was in Hudson Bay
itself, and that the Labrador ice sheet began to develop
when the main ice sheet was wasting. It is possible that it
took over as the glacial center because the supply of moisture
to feed the thinning icecap was better nearer the coast. This
might have been the result, in part, of the opening up of
water areas by the shrinking of the icecap.
Now, it follows logically that if the Wisconsin ice sheet
existed because the Hudson Bay region lay at the pole, and
if it disappeared because of a displacement of the crust that
moved North America away from the pole, then the Wiscon-
sin ice sheet must have been brought into existence as the
result of an earlier displacement. The question, therefore,
now arises, Where was the pole situated previous to its loca-
tion in or near Hudson Bay? It also becomes important to
establish as closely as possible the date of this earlier dis-
placement.
We have already discussed the date of the beginning of the
climatic change that produced the Wisconsin glaciation. A
considerable amount of evidence has now accumulated that
there were Wisconsin glacial phases earlier than the Farm-
dale (133). Furthermore, we must remember that the Farm-
dale date of 25,000 years ago is only the date of the invasion
of Ohio by the ice sheet, which had previously to advance a
long way from its center of origin. Evidence to be presented
below will strongly support the conclusion that the begin-
ning of the change of climate—that is, of the movement of
the crust— that eventually produced the Wisconsin icecap
was about 50,000 years ago. This date, as we shall see, is
not in conflict with evidence of cold climate in the North
Atlantic extending back considerably further.
With the date of the beginning of the Wisconsin glacia-
tion tentatively fixed in this fashion, it is possible, by the use
274 EARTH'S SHIFTING CRUST
of certain methods of deduction, to reach an educated guess
as to what area lay at the pole during the previous period.
The method of locating a previous polar position is simple
in principle, but very complicated in practice. The prin-
ciple is to find a point on a circle drawn about the last estab-
lished polar position with a radius of the same order of
magnitude as the distance between the present pole and the
last position. The assumption underlying this is that while
one displacement may move the crust (and therefore shift the
poles) farther than another, the chances are against any very
great differences. It seems that the last displacement, which
brought Hudson Bay down from the pole, amounted to
about 2,000 miles on the meridian of maximum displace-
ment. We shall therefore start out with the idea that the
previous displacement may have been of about the same
magnitude, but it can easily have been half as great or twice
as great. This can later be checked with the field evidence.
Our first step is to draw a circle around the hypothetical
polar position in Hudson Bay, with a radius of 2,000 miles.
Now, with a very liberal margin of error, we can assume that
the previous pole lay somewhere near that circle. Our second
step is to check the field evidence for past climates for the
whole earth to see what position on or near that circle will
explain the most facts.
The difficulties encountered in assembling the evidence
for a pole in Hudson Bay were very great, but they did not
compare with the difficulties of establishing a reasonable
case for the position of the previous pole. For this earlier
period, embracing about 40,000 years, the evidence was much
scantier. The margins of error on all climatic determinations
had to be much greater. The numerous lines of evidence
had to be examined in the light of the conscious and uncon-
scious assumptions applied to them by previous workers,
whose objectives and methods had been influenced by an
entirely different set of ideas, and whose interpretations of
the evidence might therefore be very different from mine.
EARLIER DISPLACEMENTS OF CRUST 275
The method used was that of trial and error. I selected a
possible location, and then searched the available evidence
to see whether that location was reasonable. I tried many
locations, giving up one after another as facts turned out to
conflict with each of them.
After the Hudson Bay location had been settled to my
satisfaction, I considered, for a while, that the previous posi-
tion might have been in Scandinavia. I was forced to aban-
don that idea. Other positions, investigated in turn, included
Spitzbergen, Iceland, and Alberta. There was a great deal of
shifting back and forth.
Finally, clarity began to set in; ever more numerous facts
began to fall into place, and at last I had reason to feel that
my feet were on solid ground. The previous position of the
pole was, I concluded, in or near southern Greenland, or
between Greenland and Iceland. That is, the Greenland
region then lay at the pole.
I repeated the process, with this polar position as the cen-
ter of my circle, and a rather flexible radius, and came up,
to my considerable surprise, with a pole somewhere in or
near Alaska, perhaps in the Alaska Peninsula or in the Aleu-
tian Islands. This third pole takes us back to about 130,000
years ago, and of course the evidence for it is much slighter
than that for the Greenland pole. Despite the fact that this
hypothetical position is hardly more than a suggestion to
guide further research, it is highly important because it
serves as a point of reference to "box in" the Greenland pole.
It is impossible, with the evidence now at hand, to recon-
struct any earlier displacements of the crust. However, evi-
dence of a late Pleistocene continental glaciation in Eurasia
suggests the possibility of one or two former polar zones in
that land mass. Though this evidence has been known to
Russian geologists for many years, it has attracted the atten-
tion of Western geologists only since 1946 (219). One of these
positions may account for the so-called "Riss" glaciation in
Europe.
276
EARTH S SHIFTING CRUST
90* 85' WEST FROM GREENWICH
I
S
T
95* 90* EAST FROM GREENWICH
Fig. VII. Antarctica: Three Earlier Locations of the South Pole
A corresponds to the North Pole in Alaska, B to the North Pole in Green-
land, and G to the North Pole in Hudson Bay. Positions are approximate.
At a still earlier time, western Canada may have lain at
the pole, and this may account for the so-called Illinoisan
glaciation— the ice age that preceded the Sangamon Inter-
glacial. However, since the quantity of the evidence declines
EARLIER DISPLACEMENTS OF CRUST 277
by a geometrical progression as we go backwards, clearly
these earliest suggested positions for the crust are of value
only as guides to research.
I am suggesting three displacements of the crust in the
last 130,000 years, the intervals between being of the order
of 30,000 or 40,000 years. Considering the fact that the Wis-
consin glaciation, if it started about 50,000 years ago, had
an over-all span of about 40,000 years, it is not unreasonable
to assume similar spans for the earlier periods, though per-
haps we should allow for a considerable variation of their
lengths. Whether this rapid pace was maintained all through
the earth's history is a matter that perhaps cannot be settled
at this time; however, I will discuss it briefly further on.
So far as the Pleistocene is concerned, Suess and Emiliani,
at least, see evidence that major climatic change did take
place at that rate (409:357). Their explanation that climatic
changes resulted from the cyclical astronomical curve of
solar radiation is not convincing, for reasons already made
clear.
Much of the evidence that I will use to support this sug-
gested series of displacements is in the form of cross sections
of sedimentary deposits, called cores, which often singly em-
brace very long periods of time. Rather than discuss each
core separately, the simplest method will be to assemble the
evidence from all the cores, so far as it bears on each sug-
gested polar position in turn. The lines of evidence include
marine cores from the Arctic, Antarctic, North Atlantic,
Equatorial Atlantic, and South Pacific Oceans, and the Carib-
bean Sea; many radiocarbon and oxygen isotope findings,
pollen studies, and various evidences relating to the inter-
glacial periods. The purpose of the presentation of this evi-
dence will be to explain the known major climatic changes
of the last 130,000 years, in terms of displacements of the
earth's crust. Before attempting this reconstruction of the
glacial history of the late Pleistocene Epoch, however, we
must first discuss some of the current ideas in this field.
278 EARTH'S SHIFTING CRUST
2. Weakness of the Accepted Glacial Chronology
Geologists are used to thinking of four major glaciations
during the million-year period of the Pleistocene. They have
assumed that each glaciation affected the earth as a whole
simultaneously, causing ice sheets in both Northern and
Southern Hemispheres, and lowered temperatures generally.
Some geologists have questioned this concept of four glacia-
tions; it is at least necessary to recognize several successive
phases of advance and retreat for the older glaciations.
Whether these interruptions were merely interstadials, like
those of the Wisconsin glaciation, or were true interglacials
it is increasingly hard to decide the further back in time one
goes. According to the accompanying chart of the glacial
periods (p. 282), it is evident that the intervals between the
different stages of the major glacial periods are in some cases
longer than the entire duration of the Wisconsin glaciation.
It does not seem reasonable, therefore, to insist that they
were merely interstadials, nor, consequently, to insist upon
the number of just four glaciations during the Pleistocene.
This becomes more apparent when we consider the im-
plications of the Eurasian continental glaciation mentioned
above. This, obviously, makes at least a fifth Pleistocene
glaciation, but the matter does not end there. The question
must be asked, If European geologists could overlook the
evidences of this comparatively recent glaciation until the
last decade (and this in spite of the fact that the evidences
were spread widely over two continents, and had attracted
the attention of Russian geologists as long as seventy-five
years ago), how many other glaciations in various parts of
the world may not have escaped attention? Flint has pointed
out how easily glacial evidence can be destroyed (342:171),
Coleman also emphasized the same thing:
It might be supposed that so important a change would leave be-
hind it evidence that no one could dispute, and that there should be
no room for doubt as to what happened in so recent a time of the
EARLIER DISPLACEMENTS OF CRUST 279
earth's history. In reality the proof of the complete disappearance of
the ice and its return at a later time is, in the nature of things, a
matter of great difficulty and it is not surprising that there are differ-
ences of opinion (87:20).
Croll pointed out the ephemeral character of glacial evi-
dence eighty years ago in books that are still eminently
readable. After first discussing the accumulations of strata
containing plant and animal remains during a period of
temperate climate, he comments thus on their subsequent
destruction:
. . . We need not wonder that not a single vestige of [these strata] re-
mains; for when the ice sheet again crept over the island [Britain]
everything animate and inanimate would be ground down to powder.
We are certain that prior to the glacial epoch our island must have
been covered with life and vegetation. But not a single vestige of
these is now to be found; no, not even of the very soil on which the
vegetation grew. The solid rock itself upon which the soil lay has
been ground down to mud by the ice sheet, and, to a large extent, as
Professor Geikie remarks, swept away into the adjoining seas (91:257).
It is obvious, of course, that whatever could destroy all the
surface deposits of a temperate period would also, at the
same time, destroy any evidences of former glaciations. Croll
goes on to say:
It is on a land surface that the principal traces of the action of
ice during a glacial period are left, for it is there that the stones are
chiefly striated, the rocks ground down, and the boulder clay formed.
But where are all our ancient land surfaces? They are not to be found.
The total thickness of the stratified rocks of Great Britain is, accord-
ing to Professor Ramsay, nearly fourteen miles. But from the bottom
to the top of this enormous pile of deposits there is hardly a single
land surface to be detected. True, patches of old land surfaces of a
local character exist, such, for example, as the dirt beds of Portland;
but, with the exception of coal seams, every general formation from
top to bottom has been accumulated under water, and none but the
under-clays ever existed as a land surface. And it is here, in such a
formation, that the geologist has to collect all his information regard-
ing the existence of former glacial periods. . . .
If we examine the matter fully we shall be led to conclude that
the transformation of a land surface into a sea-bottom (by erosion and
EARTH'S SHIFTING CRUST
deposition of the sediments) will probably completely obliterate every
trace of glaciation which the land surface may once have pre-
sented. . . .
The only evidence of the existence of land ice during former
periods which we can reasonably expect to meet with in the stratified
rocks, consists of erratic blocks which may have been transported by
icebergs and dropped into the sea. But unless the glaciers of such
periods reached the sea, we could not possibly possess even this evi-
dence. Traces in the stratified rocks of the effects of land-ice during
former epochs must, in the nature of things, be rare indeed (91:267-
69).
Croll was interested in pointing out the impermanence of
glacial evidence. He continued, therefore, as follows:
The reason why we now have, comparatively speaking, so little
direct evidence of former glacial periods will be more forcibly im-
pressed upon the mind, if we reflect on how difficult it would be in a
million or so of years hence to find any trace of what we now call the
glacial epoch. The striated stones would by that time be all, or nearly
all, disintegrated, and the till washed away and deposited in the
bottom of the sea as stratified sands and clays. . . . (91:270).
In view of the facts presented by Croll, it would appear to
be most unreasonable to insist on any fixed number of
Pleistocene glaciations simply because hitherto it has been
possible to group, in a very rough way, the comparatively
few evidences we have in four glacial periods.
It is a well-known fact that the chronology of four Pleisto-
cene glaciations has been built up on the foundation of the
assumption that all glacial epochs were the result of lowered
world temperatures. Thus the European glaciations were
declared to have been contemporary with the glaciations in
America, although, as a matter of fact, no evidence of this
existed. The assumption was based solely on astronomical
and other theories of the causes of glaciation that we have
shown to be inadequate. If the grouping of all European
glacial evidences into only four major glaciations is ques-
tionable, and if, in addition, there is no good evidence that
these glaciations were really contemporary with those in
America, then the possibility of a large number of different
EARLIER DISPLACEMENTS OF CRUST 281
glaciations in America and Europe during the Pleistocene
must be taken seriously.
If the number of these alleged major Pleistocene glacia-
tions is not satisfactorily established, the attempts at dating
them leave even more to be desired. A review of the past and
current literature on the subject reveals lack of agreement.
Estimates vary widely, and none of them has convincing sup-
port. To make this plain, it is only necessary to compare the
various estimates. The table on page 282 shows the estimates
made by Penck and Bruckner, considered the leading Euro-
pean experts (whose work, however, was done before the de-
velopment of nuclear techniques of dating), and by Zeuner,
whose estimates were endorsed by the climatologist Brooks.
The reader will note that Zeuner divides each of the older
glaciations into a number of substages, some of which are
longer than the entire period covered by the Wisconsin
glaciation. The reader will recall that the interstadials and
the successive advances of the Wisconsin glaciation had dura-
tions of the order of two or three thousand years; he may
also note in the various cores shown later on that all the
cores show brief climatic changes of the same magnitude. It
is therefore impossible to concede that the earlier glaciations
could have had interstadials 40,000 or more years long. The
only explanation ever advanced for the oscillations of the Wis-
consin ice sheet that I know of is the one advanced in this
book: massive volcanism caused by displacement of the crust.
This explanation cannot, however, be reasonably applied to
oscillations 40,000 years in length.
We see that the estimates of Zeuner (52: 107) and of Penck
and Bruckner (52:107) are in profound disagreement.
It would be easily possible to multiply the number of such
contradictory estimates, or, if the reader pleases, he may ac-
cumulate authorities who will support one of them; but is
it not obvious that if leading professional geologists can differ
to such an extent, no real reliance can be placed upon any of
their very approximate and very speculative estimates? And
28*
EARTH'S SHIFTING CRUST
TABLE II
The Pleistocene Glaciations
Zeuner
(European)
Wurm Glaciation
Stage III 25,000
Stage II 72,000
Stage I 115,000
Riss Glaciation
Stage II 187,000
Stage I 230,000
Mindel Glaciation
Stage II 435,000
Stage I 476,000
Gunz Glaciation
Stage II 550,000
Stage I 590,000
Penck 8c Bruckner
(European)
40- 18,000
130-100,000
430-370,000
520-490,000
when, in addition, we find they have all been wrong as to
the number of Pleistocene glaciations— since a fifth one has
just turned up— are we not justified in dismissing all these
estimates as speculations that are no longer worth discussing?
If there is any doubt as to the reasonableness of this con-
clusion, it should be put at rest by an entirely new estimate
of the glacial chronology just produced by Emiliani. Emili-
ani, working with marine cores, and applying some of the
new techniques of dating, has found that the earliest Pleisto-
cene glaciation occurred only 300,000 years ago, and that all
the four recognized European glaciations, and their alleged
American counterparts, have to be compressed into that
comparatively short period (152). This finding, which there
is no rational reason to reject, completes our picture; it
EARLIER DISPLACEMENTS OF CRUST 283
disposes, finally, it seems to me, of the traditional glacial
chronology of the Pleistocene.
As a consequence of this breakdown of the old theory, it
seems to me that we must now start from the beginning, and
build a new glacial chronology of the Pleistocene. Our
method can only be the tested method of science: to proceed
from the known to the unknown; from the Wisconsin gla-
ciation, where our information is most ample, backwards.
3. The Beginning of the Wisconsin Glaciation
Examination indicates that, with the elimination of some
mutually contradictory and evidently disturbed sediments,
the three Ross Sea cores show a change from the deposition
of glacial sediment to the deposition of temperate sediment
on the Ross Sea bottom 40,000 years ago (p. 306). As a first step
in establishing an approximate date for the beginning of the
climatic change (that is, for the beginning of the movement
of the crust) that was to produce, simultaneously, the tem-
perate age in Antarctica and the glacial age in North Amer-
ica, we must interpret the meaning of this change in the
sediment.
In the first place, the date itself is subject to some doubt.
Two cores show the change at 40,000 years ago; one shows it
a few thousand years later, but at the same time it also shows
a change at 40,000 years ago from one type of glacial sedi-
ment to another. The change in that core is from coarse to
fine sediment, which in itself indicates amelioration of cli-
mate. Thus, all three cores indicate at least some warming
of the climate about 40,000 years ago.
Now, what lapse of time must we allow between the be-
ginning of the change of climate in Antarctica and the result-
ing end of glacial deposition on the Ross Sea bottom? In the
first place, we must remember that the movement of the crust
would at first be entirely imperceptible. The speed of
the displacement would increase slowly. After several thou-
284 EARTH'S SHIFTING CRUST
sand years a warming of the climate would be noticeable
in the areas moving equatorward, and a cooling of the
climate would occur in areas moving poleward, but these
long-term trends of change would often be modified or
even reversed by other factors. Massive volcanism would
erupt before the crust had moved far, and the effect might
be to check the retreat of the icecap, and even to cause its
readvance after it began to retreat. We can see that this seems
to have happened with the Wisconsin icecap: for thousands
of years after it began to grow thinner, and to retreat, it
went through phases of readvance.
Before the final disappearance of glacial sediment from the
Ross Sea bottom about 40,000 years ago, then, we must as-
sume that the icecap then in Antarctica had gone through
an initial phase of very gradual retreat, followed by perhaps
several phases of readvance, until finally it withdrew entirely
from the Ross Sea coast, and melted sufficiently to permit
free-flowing rivers to bring down temperate-type sediment
from the interior. It seems obvious, on the analogy of the
Wisconsin icecap, that we should allow a period of time of
the order of 10,000 years or so for this entire process. This
suggests, then, that the movement of the crust began about
50,000 years ago. However, it does not mean that the move-
ment ended 40,000 years ago; it might even have continued for
another 10,000 years. The cores contain no evidence on that
point. It may have taken much more than 10,000 years to
shift the crust. The core evidence, however, may be used to
support the thesis that the crust displacement that brought
the Hudson Bay region to the pole started about 50,000 years
ago. In the following discussion we will tentatively consider
that the previous position of the pole was in southern Green-
land.
a. The Arctic Cores
In the last few years Soviet expeditions in the Arctic Ocean
have taken a number of deep-sea cores, and have dated them
EARLIER DISPLACEMENTS OF CRUST 285
by the ionium method. These cores provide impressive con-
firmation of the situation of the pole in North America dur-
ing the Wisconsin glaciation, and, in addition, they furnish
evidence of the approximate date of its migration to the
Hudson Bay region from its previous position.
The Soviet scientists were much impressed by their dis-
covery that in the comparatively short period of the last
50,000 years there have been no less than six major changes
of climate in the Arctic Ocean. They did not find it easy to
explain all these changes. They may all be explained, how-
ever, by the hypothesis of two displacements of the earth's
crust.
The period begins with a very cold phase. Since the cores
go back only 50,000 years, we do not know when the cold
period began. The scientists remark:
It seems that in the period in question, a considerable part of the
Arctic shelf was dry; ther£ was no, or almost no, communication with
the Atlantic. The climate was cold (364:9).
According to the principles already set forth (Chapter IV),
a pole in southern Greenland might be expected to have
coincided with higher elevation of that general region, in-
cluding the adjacent sea bottoms. The continental shelves
in that part of the Arctic Ocean facing toward Scandinavia
might well have been raised above sea level. There might
well have been a land connection between Greenland and
Iceland, and even across the narrow North Atlantic to Scan-
dinavia. The Soviet scientists themselves strongly suggest
that this land connection must have existed; nor are they
alone in their suggestion. Years ago Humphreys advanced the
idea. More recently Malaise has produced much new evi-
dence for it (2 91 a). Thus it is evident that our theory has
started out pretty well, by explaining why there was little
communication between the two oceans. The interruption,
however, was not simply the result of land masses in the
North Atlantic. It could also have been the result of having
a polar area lying right across the connections between the
286 EARTH'S SHIFTING CRUST
Arctic and the North Atlantic. A glance at the globe will
make this clear.
Beginning 50,000 years ago, and lasting for about 5,000
years, there was, according to the Soviet scientists, a brief
warm spell in the Arctic Ocean:
. . . The bottom sediments became finer; argillaceous and highly
argillaceous oozes began to be deposited, of a brown or here and
there dark brown color, with increased contents of iron oxides, man-
ganese, and foraminiferous micro-fauna (364:9).
This warm period may reflect the movement of the crust
that resulted in withdrawal of the pole from Greenland and
its shift toward Hudson Bay. It is followed, however, by a
cold period in the Arctic from 45,000 to 28-32,000 years ago.
This following cold period is explained, according to our
theory, by the beginning of the subsidence of the land bridge,
which may have opened a water connection between the two
oceans. The pole was at this time still near the Atlantic, and
very cold Atlantic water was thus able to pour into the
warmer Arctic. The subsidence of the land bridge as the pole
moved away is, of course, a corollary of our theory. Such a
subsidence in any area moving away from a pole would posi-
tively have to occur, unless counteracted locally by the reloca-
tion at particular points under the crust of lighter rock de-
tached from the underside of the crust elsewhere.
Following this cold period in the Arctic, we come to a
most remarkable change, one which, in my opinion, provides
an unusually impressive confirmation of our assumption of
the location of the Hudson Bay region at the pole. About
28-32,000 years ago, a really warm period began in the
Arctic, and lasted until 18,000 to 20,000 years ago. The
Soviet scientists have found that during this period there was
a rich development of temperate-type microfauna in the
Arctic, though their explanation is very different from ours:
. . . The luxuriant development of a foraminiferal fauna of North
Atlantic type testifies that during this period warm Atlantic waters
were invading the Arctic Basin on a broad front; that is, communica-
tion between the Arctic Basin and the Atlantic Ocean, which had
EARLIER DISPLACEMENTS OF CRUST 287
apparently been interrupted in the previous period, was reestablished.
The duration of the warm period has been set at approximately ten
to twelve thousand years (364:11).
According to our interpretation, this luxuriant develop-
ment of microorganisms of temperate type in the Arctic
Ocean marks the movement of the pole into the interior of
North America, and away from the Atlantic. This movement
must have initiated a temperate period in all that half of the
Arctic Ocean facing Scandinavia and Siberia. Again, a glance
at the globe will make this clear. The reader cannot fail to
see that with the pole in Hudson Bay, the Arctic and the
Atlantic Oceans would lie on the same temperate parallel of
latitude.
This indication of temperate conditions in the Arctic
gains enormously in significance when considered in connec-
tion with the evidence of the Ross Sea cores for the same
period in Antarctica. It seems that here we have evidence of
warm periods near both the present poles. Yet, obviously, it
is impossible to claim that the whole earth was warmer at the
time, because of the evidence of widespread glacial condi-
tions in both North America and Europe. It seems to me
that a reasonable person is forced to the conclusion that the
crust shifted.
b. Earlier Phases of the Wisconsin Glaciation
Let us briefly reconstruct the history of the crust displace-
ment that resulted in the shift of the polar location from
Greenland to Hudson Bay. This will explain the earlier,
unknown phase of the Wisconsin glaciation. As has been
pointed out, the earliest known phase of that glaciation is the
Farmdale, only 25,000 years ago. Despite this fact, very many
pieces of wood and other remains from glacial deposits in
North America have been found to be much older than that.
As already mentioned, Flint was led by this evidence to sug-
gest that there must have been earlier glacial advances, the
evidences of which were later destroyed. It has been shown
288 EARTH'S SHIFTING CRUST
that the Mankato Advance of the ice sheet occurred only
1 1,000 years ago, and yet some deposits of Mankato age con-
tain pieces of wood that have been found to be more than
30,000 years old. These must have been included originally
in older glacial deposits.
Our theory may explain not only the earlier phases of the
Wisconsin glaciation but also why most of their traces were
destroyed. Let us assume that 50,000 years ago the previous
crust displacement started shifting the pole from southern
Greenland toward Hudson Bay. This would have started an
expansion of glaciation in North America, with the ice mov-
ing toward the west and south. We must visualize a gradual
lowering of the temperature over a period of several thousand
years, with those sudden changes resulting from volcanism
with which we are already familiar. In this case, instead of
each advance of the icecap falling short, at least in some
places, of the preceding advances, so as to leave traces in the
form of undisturbed moraines, the contrary happened. As the
crust moved, the pole was steadily advancing from the north-
east, and therefore each phase of expansion of the ice sheet
would naturally carry the ice front farther than the one be-
fore, plowing up and destroying the evidences of earlier
phases, obliterating the record and incorporating the older
glacial material with its own debris. Not until the climax of
the glaciation was reached, with the Farmdale Advance, did
a change in this situation occur. The date of this advance,
therefore, may have been the time when the Hudson Bay
region reached the pole and the crust ceased to move.
</. Greenland at the Pole
Several impressive lines of evidence are in accord with the
assumption of the location of the general region of southern
Greenland at the pole before the time when the Hudson Bay
region may have been located there. In considering these
lines of evidence, we shall assume that the period during
EARLIER DISPLACEMENTS OF CRUST 289
which Greenland was at the pole was of the order of 30,000
or 40,000 years, or that it was roughly comparable in length
to the period when Hudson Bay lay at the pole. This will
carry us back, therefore, about 90,000 years.
The assumption of a pole in southern Greenland seems
able to solve a remarkable number of climatic problems per-
taining to various parts of the world. In the first place, it can
explain the evidence that indicates that the glacial period in
Europe began earlier than the Wisconsin glaciation. It is
consistent with the existence in New York State of the tem-
perate fauna and flora which we saw were enclosed in the
Wisconsin ice sheet. It would explain, as nothing else has
explained, why the massive European ice sheet advanced
southward only as far as the 5oth parallel of latitude, while
in North America the Wisconsin icecap extended southward
to the 4oth. A glance at the globe will be sufficient to show
the reader the truth of this. In addition, this position of the
pole will explain two different problems in Antarctica. On
the om .and, in many parts of Antarctica, as already men-
tioned, there are glacial striations above the present level of
the ice, indicating that a thicker ice sheet once existed in
those areas; on the other hand, the Ross Sea core N— 4 (see
Figure XI, p. 306) indicates temperate-type sediment on the
bottom of the Ross Sea from about 65,000 to about 80,000
years ago. Now this continuous deposition of temperate sedi-
ment on the bottom of the Ross Sea for nearly 20,000 years
is very difficult to explain. It quite obviously cannot be ex-
plained at all in terms of the present position of the pole.
If the reader will turn to the map of Antarctica (p. 276) on
which I have indicated the various positions of the South
Pole corresponding to our Hudson Bay, Greenland, and
Alaskan North Poles, he will note that a South Pole corre-
sponding to our Greenland North Pole would imply a
thicker ice sheet than now in some parts of Antarctica. So
far as the Ross Sea is concerned, an interesting situation
emerges. It seems probable that the side of the Ross Sea near-
est this former South Pole would be glacial, while the other
290 EARTH'S SHIFTING CRUST
side may have been nonglacial. Thus sediment of both kinds
could be deposited in different parts of the Ross Sea at the
same time, depending, perhaps, to some extent, on the local
peculiarities of bottom topography and bottom currents. It
cannot be assumed, of course, that the outlines of the conti-
nent, or the depths of the surrounding oceans, were the same
at that time as they are now. However, those who may still
be inclined to discount the theory presented in this book
must be reminded that all the phenomena discussed in this
chapter— and all the principal phenomena discussed in this
book— have been hitherto unexplained. It is not a question
of choosing between explanations. There is, at the present
time, no other explanation than ours of these facts.
a. Cores from the San Augustin Plains
A good deal of evidence from other cores supports this suc-
cession of polar positions in Greenland and Hudson Bay.
Let us consider first a very interesting study recently made in
New Mexico. There a group of scientists have been studying
a very long sedimentary core taken from the San Augustin
Plains. On these plains, sediments have accumulated to a
great depth without consolidating into rock, so it has been
possible to bore down about 645 feet and get a cross section
of all the deposits to that depth. These sediments contain
pollen of various trees and plants, which, as is well known,
does not easily disintegrate, but remains preserved in the soil
for very long periods. In this core, different kinds of pollen
in the different layers indicated changes in the species of trees
and plants growing in the region, and of course changes in
the kinds of plants growing in a region indicate changes of
climate. For the upper and most recent part of the core, it
was possible to use the radiocarbon method to date the
changes in pollen types, and therefore in climate.
Figure VIII (opposite page), prepared by Drs. Clisby and
Sears (84), shows the climatic curve for the upper 330 feet
of the core. The radiocarbon date at 27,000 years ago plus
POLLEN PERCENTAGE
SAND— >
10 20 30 40 50 60 70 80 90 100
4-19,000* 1,600
, 0 00 * 5,000- 3,200
K DESERT
I- VCHENOPODIACEAE
Fig. VIII. Pollen Profile from the San Augustin Plains, New Mexico
EARTH'S SHIFTING CRUST
5,000 or minus 3,200 years (an unusually large margin of
error) indicates glacial conditions at that time, and a rough
extrapolation based on the rate of sedimentation indicated
for the dated part of the core would indicate that glacial con-
ditions began in New Mexico not more than about 40,000
years ago. A most remarkable thing about this core is that it
indicates temperate conditions from this point all the way
down to the bottom. When it is considered that the older sec-
tion dated by radiocarbon, about 27,000 years old, was only
28 feet down in the core, it is evident that the core covers a
very long time.
This climatic record has some very important implications
for us. It appears to show, for one thing, that the glacial
period in North America generally did not extend back as far
as the glacial period appears to have done in the North At-
lantic and in Europe. It seems to show, unmistakably, that
the so-called Sangamon Interglacial continued without a
break, down to about 40,000 years ago, at least in western
North America. Thus, it implies that the Sangamon Inter-
glacial in North America was contemporary with the earlier
part of the Wiirm glaciation in Europe. This is a remarkable
state of affairs, and appears to dispose irrevocably of the doc-
trine of the simultaneousness of glaciations. Incidentally, it
provides confirmation of climatic conditions in New York
State suitable for the mastodons and other animals that lived
there before the growth of the Wisconsin icecap. It is there-
fore in agreement with our assumption of a pole in southern
Greenland. This core, the data considered above from North
America and the Arctic, and the Antarctic cores give us a tri-
angulation that provides extraordinarily strong confirmation
of the theory.
There is one factor, however, that may enter into the inter-
pretation of this San Augustin core, which could invalidate our
conclusions. The plains are now at an elevation of 7,000 feet
above sea level. The earlier chapters of this book have ex-
plained how displacements of the earth's crust may cause
major changes in land elevations. A change in land elevation
EARLIER DISPLACEMENTS OF CRUST 2Q3
would, of course, affect the climate and therefore the vegeta-
tion growing in an area. It is generally considered that 1,000
feet in elevation is the equivalent of about eight hundred
miles in latitude, so far as plant habitats are concerned. We
therefore have to take into consideration the possible effect
of an uplift of the plains during the time that the sediments
were accumulating. In view of the fact that the 645 feet of
sediments may easily embrace a total period of time exceed-
ing a million years, or the length of the whole Pleistocene
Epoch, and since we have evidence that there were a number
of ice ages in North America during the Pleistocene, before
the Wisconsin glaciation, we may be forced to assume that
there was a considerable uplift of the plains during the
Pleistocene. However, it is reasonable to suppose that during
the comparatively short period we are now discussing— the
period from about 40,000 to about 90,000 years ago— the up-
lift may not have been of major proportions.
Our Greenland pole is supported by other lines of evi-
dence. In evaluating them, however, we shall have to take
into consideration the still earlier hypothetical position of
Alaska at the pole.
b. Some North Atlantic Cores
A number of cores have been taken in the North Atlantic,
and dated by the new methods of absolute dating. Despite
the fact that these cores were obtained independently by
different scientists, and dated by different methods, we shall
find that they agree well, and that they support our basic
assumptions.
The cores to be considered include three taken from the
North Atlantic in about Lat. 46-49° N., and dated by the
ionium method, and three cores from the Caribbean and
the Equatorial Atlantic.
The last three cores were prepared by Ericson, who ana-
lyzed their enclosed foraminiferal remains for evidence of
climatic change. They were subjected to radiocarbon tests by
294 EARTH'S SHIFTING CRUST
the United States Geological Survey. They were also studied
by Dr. Cesare Emiliani, who used a technique developed by
Dr. Harold C. Urey for determining ancient water tempera-
tures. This technique makes use of an isotope of oxygen
(Oi8) the proportion of which in sea water is affected by
temperature. The temperature of the water at which ancient
shells grew (or, in this case, at which foraminiferal micro-
organisms grew) can be determined by the proportion of
Ois in the remains. This determination is independent of
time, and the temperature at which a shell grew 200,000,000
years ago (but not the date) can be determined just as well
as if the shell grew last year. Emiliani used this technique to
establish temperature curves for the sedimentary cores for
the period within the range of radiocarbon. Then, using this
as a base, he extrapolated to the older parts of the cores.
There is reasonably good agreement between temperature
curves arrived at in this way and those obtained by the
ionium method.
Of the three cores taken from the North Atlantic and
dated by the ionium method, one extends back to only 1 1,800
years ago, one to 24,300, and one to 72,500. The longest core
will have the greatest interest for us (Figure IX).
Core P- 12 6(5) was taken in mid- Atlantic, approximately at
the latitude of Nova Scotia, in about three miles of water.
Since it extends back to 72,500 years ago, it should be able
to throw some light on the question of our assumed polar
positions, including the Alaskan.
The story of this core, as we recede into the past, is as
follows: There is first a layer of volcanic glass shards, dated
about 12,800 years ago, then a layer of nonglacial sediment,
then glacial sediment from 14,700 to 23,700 years ago, then
nonglacial sediment but with evidence of cold water, back
to 60,700 years ago. This period of cold water is interrupted
by three brief intervals of glacial deposition, by two layers of
confused ("anomalous") sediments, and by a layer of volcanic
glass shards between 51,400 and 55,400 years ago. Then, be-
tween 60,700 and 68,000 years ago, the North Atlantic water
EARLIER DISPLACEMENTS OF CRUST
P-130 (9)
P-124 C3)
P-126 (5)
300
800
NAUTICAL MILES
Fig. IX. Chronology of Sediments in the North Atlantic Cores P- 124(3),
P-i*6(5), P-iso(9)
gets warmer, until it becomes definitely warmer than it is
today. The warm period continues to the bottom of the core.
This core raises some enormously interesting questions.
In the first place, it indicates very cold conditions, much
colder than the present, in the North Atlantic back to about
62,000 years ago, and we must ask, How can this be recon-
ciled with the indications of a climate like the present on
the San Augustin Plains for the same period? We shall see
that the other cores, from the Caribbean and the Equatorial
Atlantic, will intensify this contradiction, for they confirm
the cold climate in the Atlantic. These cores constitute evi-
dence for a pole in the Greenland region.
296 EARTH'S SHIFTING CRUST
A second vital question raised by the core is the existence
of a warm North Atlantic 70,000 years ago: the foraminiferal
studies made in connection with this core show that the
North Atlantic was warmer then than now. There has been
no explanation of this, yet obviously it is enormously im-
portant. It may be explained by a polar position in the
Alaskan region. We will return to this question in connec-
tion with the other evidences for the location at that time
of Alaska at the pole.
Deposits of volcanic glass shards are not, from our point of
view, something to be passed over without remark, especially
when, as in this case, the deposits relate themselves remark-
ably well to critical phases of our assumed crust displace-
ments. The last such deposit agrees in time with the Gary
Advance of the Wisconsin ice sheet, and may be considered
as possible evidence of the intense volcanism that may have
accompanied and, indeed, caused that glacial advance. The
older band of volcanic shards also apparently coincides with
a time of great change, as indicated by the Arctic cores al-
ready discussed. That was the time when, according to our
theory, the displacement started that was to shift Greenland
from, and Hudson Bay to, the pole.
It appears to me that the dating of the brief intervals of
glacial deposition also has significance. For example, a brief
interval of glacial deposition between 50,000 and 51,200
years ago immediately follows the deposition of volcanic glass
shards, which according to our theory can have represented a
period of massive volcanism, which may have acted as the
direct cause of the glacial advance, which, in turn, may have
led to the deposition of the glacial sediment in the sea. Of
course the finding of volcanic debris and glacial sediment in
sequence in the same core is an accident in one sense, for a
prolonged episode of massive volcanism anywhere else on
the surface of the earth would have produced the advance of
glaciers adjacent to the Atlantic. During any movement of
the crust, we may assume that volcanism would be very active
in many parts of the earth, and not necessarily in the immedi-
EARLIER DISPLACEMENTS OF CRUST 2Q7
ate neighborhoods of the ice sheets. The oldest episode of
glacial deposition, about 60,000 years ago, coincides closely
with the time that we have assigned hypothetically for the
maximum of the Greenland glaciation.
A serious problem is presented by the fact that the sedi-
ment deposited in the North Atlantic during the period from
23,700 to about 60,000 years ago is not actually glacial except
for brief episodes. How can this be accounted for if we are
to assume a pole in Greenland? For that matter, how can it
be accounted for if we are to extend the Wurm glaciation in
Europe back as far as the European geologists seem to de-
mand?
It is obvious, from the brief recurrent episodes of glacial
deposition, that somewhere an ice sheet or ice sheets lay near
the coasts, so situated that when expanded in the brief
periods of greater cold brought on by massive volcanism, one
or more ice sheets reached the sea. It may be necessary to
consider that the pole in Greenland may not have been very
near the sea at that time, and, as I have already suggested, a
number of authorities are now receptive to the idea of a land
connection across the North Atlantic.
c. A North Atlantic Land Mass?
This, in turn, produces another problem. If there was a land
connection across the North Atlantic, and if the pole was in
southern Greenland, would not the continental ice sheet
have entered the British Isles from the northwest, instead
of from the northeast, from the direction of Scandinavia?
Strangely enough, a very persuasive book has been written
by Forrest (164) to sustain precisely this thesis. I have spent
considerable time checking his sources. I have gone through
many of the original reports he used, including numerous
field reports published by the British Association for the
Advancement of Science, the Liverpool Geological Society,
and other British geological societies. I have also checked
secondary works by various British geologists. As a result I
298 EARTH'S SHIFTING CRUST
have found an impressive mass of reliable direct field ob-
servation indicating that the original direction of the ice
invasion of the British Isles, in the earlier part of the ice age,
was from the northwest. In most areas the evidences of the
movement were later overlaid or destroyed by the Scandi-
navian ice sheet, or by local glaciers.
In reviewing the field reports, and later the general geolog-
ical works that used the reports as source material, I have
noticed a most interesting phenomenon. Field observers
quite often remarked on the northwest-southeast directions
of certain glacial striations, on associated glacial evidences
showing clearly that the ice moved from the northwest
toward the southeast, and on evidence that the ice sheet
swept over the tops of most of the mountains of Ireland,
Wales, and Scotland, often across the axes of the valleys, and
from the northwest. But as the discussion of the subject was
removed from direct contact with the field, and as the field
reports were condensed, abstracted, and interpreted, this evi-
dence of ice movement from the northwest became more and
more subordinated, and, finally, was lost to view. The reason
for this is quite simple. The geologists were firmly convinced
that the ice sheet could have come only from Scandinavia.
An ice center in the North Atlantic, involving former land
areas in that region, was quite unthinkable. This was a
natural consequence of the general acceptance of the theory
of the permanence of continents. Various ingenious solutions
of the problem were suggested. Charlesworth pointed out that
a westward-trending valley could turn an ice sheet descend-
ing from the British highlands westward, and it might fan
out on the coastal plain, so that its northern flank would actu-
ally be moving toward the northwest. Other geologists have
stressed glaciers expanding in all directions from elevated
areas in Britain. The awkward thing is that precisely what
these people assert happened probably did happen, but in
the later part of the ice age, when the North Atlantic ice
center was gone, the Scandinavian glacier lay along the east
coast of Britain, and local valley glaciers occupied the in-
EARLIER DISPLACEMENTS OF CRUST
terior. Nobody, however, has properly examined the data
cited by Forrest as his principal line of evidence.
Recently Kolbe and Malaise have produced evidence that
may cause many to turn to the work of Forrest with new
interest. From the evidence of fresh-water diatoms indicating
a former fresh-water lake on the mid-Atlantic ridge, now
about two miles below the surface of the ocean, and from the
study of the differing sediments deposited on the two sides
of the ridge, Malaise reaches the conclusion that the mid-
Atlantic range was above sea level until the end of the Pleis-
tocene (2gia:207).
Unfortunately, limitations of space must prevent further
discussion of this question. I can only refer the reader to the
works cited and to Forrest's original sources. Forrest has
made a few mistakes in discussing matters dealing with ice
sheets, but he himself calls attention to the fact that he was
trained as a zoologist, not a geologist. However, his errors are
not such as to affect the validity of his argument. The prin-
cipal weakness of his book is that he does not present the
evidence in sufficient detail, so that it is necessary to refer to
the original sources.
It is possible that the displacement of the crust that re-
sulted in the movement of the pole from Alaska to Green-
land may itself have raised the North Atlantic bpttom enough
to bring a transatlantic land connection, in the manner sug-
gested in Chapter IV, and that in consequence the Greenland
ice sheet may have travelled along the land bridge into
Britain. The subsequent displacement that shifted the pole
toward Hudson Bay could have brought about the resub-
mergence of parts of the land bridge, and have resulted in the
destruction of the Greenland continental glacier. The final
movement of the pole to its present location could have re-
sulted in the submergence of the remnants of the land bridge.
The advantage of our hypothesis is that it seems able to
suggest both the cause of the creation of a land connection
across the North Atlantic, and the cause of its disappearance.
The fact that we have here two successive displacements of
joo EARTH'S SHIFTING CRUST
the crust helps us to account for the total amount of the
submergence. Each of these hypothetical movements would
have shifted the North Atlantic nearer the equator, and
therefore, according to the theory, would have favored sub-
sidence of land area relatively to sea level. The evidence of
very widespread volcanism in the whole basin of the North
Atlantic during the ice age (174) carries the implication,
also, that invasion of the lower parts of the crust by molten
magma of high density could have weighted and depressed
the area, in the manner suggested earlier (Chapter VI).
d. Additional Atlantic Cores
To return to our Atlantic cores, a rather interesting point
about Core P~i26(5) is that the deposition of glacial sedi-
ment ceased about 14,000 years ago. It may be noticed, how-
ever, that in another of the Urry cores, P-i3o(g), which was
taken much farther to the east, the deposition of glacial sedi-
ment ceased 1 8,000 years ago. One might at first be inclined
to pass this over as an unimportant detail, until one realized
that with Hudson Bay at the pole the difference is com-
pletely explained. Under those circumstances, the second
core, which now lies to the east, would have been due south
of the first core, and it would be entirely natural that the
warming of the climate at the end of the ice age would be
felt first in the more southerly region. This, then, constitutes
additional evidence for the location of the Hudson Bay
region at the pole during the period of the Wisconsin glacia-
tion.
We have still to consider the Ericson-Suess-Emiliani At-
lantic cores. I reproduce, below, Suess's graph of the tempera-
ture changes in the Atlantic for the last 100,000 years, as
evidenced by these cores.
Now, to begin with, we note that according to these cores
the temperature of the Atlantic Ocean was at a peak between
75,000 and about 98,000 years ago; this agrees substantially
with the Urry core already discussed, but extends the warm
EARLIER DISPLACEMENTS OF CRUST
40 50
1000 YEARS -
60
70
eo
90
Fig. X. North Atlantic Cores A 172-6, A 199-4, A 180-75
period back to about 100,000 years ago. We will assume that
this warm phase in the Atlantic represents the period, or at
least the latter part of the period, when Alaska was at the
pole.
We note, too, that the temperature in the Atlantic during
this warm period was not, at the sites of these cores, as high
as the temperatures now prevailing there, except for two
very brief spurts in Cores A 180-75 and A 179-4. Yet we
have seen that the Urry core P- 12 6(5) indicated clearly that
the water was warmer at that time than it is at present. How
is this conflict to be solved? Shall we be forced to discredit
the reliability of one finding or the other? Not at all. Our
theory offers the possibility of eliminating this apparent con-
tradiction in the evidence.
Let us consider the present and past latitudes of these
cores. P-i26(5) was taken in about the latitude of St. John's,
Newfoundland; the others were taken in very low latitudes.
EARTH'S SHIFTING CRUST
If we assume that Alaska was at the pole during this warm
period in the Atlantic, the site of this core would then have
been farther from the pole than it is now; that is, it would
have been south of its present latitude. Quite naturally the
water would have been warmer. A glance at the globe will
suffice to make this plain.
On the other hand, if we now consider Core A 180-75,
taken in the eastern Equatorial Atlantic, nearly on the
equator, the opposite situation is revealed. A pole in Alaska
would displace this core southward from the equator, pos-
sibly as far as the 2Oth parallel of South Latitude (depending,
of course, on the precise location of the pole in Alaska).
Quite probably, the water would be colder then than it is at
present, other things being equal.
The two Caribbean cores would, with the Alaskan pole,
have had approximately the same latitude as at present; the
uncertainty as to the precise location of that pole makes it
impossible to draw any reliable conclusions from them.
Both the Caribbean cores indicate a temperature mini-
mum about 55,000 years ago, which would correspond well
with the date we have tentatively assigned for the arrival of
Greenland at the pole; they both show the temporary warm
period that was shown in the Arctic cores, which we have
interpreted as marking the breakup of the Greenland conti-
nental icecap. They then show a gradual temperature decline
from about 40,000 to about 1 1,000 years ago, which may cor-
respond, first, to the growth of the Wisconsin continental
icecap and, finally, to the movement of the ice center of that
icecap eastward into Labrador during the declining phases of
the glaciation.
At this point it is important to consider a contradiction
between the Caribbean cores and the core from the eastern
Atlantic. It appears that the ocean temperature reached its
minimum, after the early warm period, in the eastern At-
lantic about 20,000 years before it did in the Caribbean.
This is a very important difference. How is it to be ex-
plained?
EARLIER DISPLACEMENTS OF CRUST
It appears that this anomalous fact may constitute, in it-
self, one of the most impressive confirmations of the whole
theory of displacements of the crust, for, if you look at a
globe and visualize the shift of the crust that moved Alaska
from, and Greenland to, the pole, and if you use a tape
measure to measure the distances from each polar position
to the Caribbean and to the equator off the bulge of Africa,
you will see that that particular polar shift should make only
a comparatively slight change in the latitude of the Carib-
bean, but a very radical change indeed in the latitude of the
eastern Equatorial Atlantic. And since the movement would
take the same period of time in both cases, the rate of move-
ment would necessarily be much more rapid in the eastern
Atlantic, and this both agrees with and explains the core
evidence.
5. Alaska at the Pole
We have already seen that the assumption of Alaska's posi-
tion at the pole between about 80,000 and about 130,000
years ago helps to solve a number of important problems.
The idea for this position first occurred to me when I
learned of the work of Arrhenius (i3a), who took cores
from the North Pacific and found that there was a fall of
temperature in that area about 100,000 years ago. He de-
cided that that fall of temperature must have marked the
beginning of the ice age everywhere. But as we have seen,
the evidence shows that this "ice age" began at very different
times in different areas. We are forced to develop a theory
that will explain why the ice age developed in different areas
at different times.
I fully realize that this suggestion of one previous polar
location before another in an apparently endless succession
may cause some discomfort to the reader. He may be willing
to settle for the Hudson Bay pole; after all, the evidence is
rather overwhelming. The Greenland pole may be worth
304 EARTH'S SHIFTING CRUST
considering, because after all it at least makes sense of the
radiocarbon datings and the Atlantic marine cores. But this
Alaskan proposition is, he may think, going altogether too
far. Where will we end? Is the whole history of the earth
to be considered in terms of this hop, skip, and jump of the
poles? And is it conceivable that this sort of thing could have
kept up for two billion years?
If the reader is having this sort of crisis of belief, I suggest
that he consider the matter in this light: one shift of the
crust, at the end of the ice age, has been pretty well demon-
strated. Another one, at the beginning of the ice age, is neces-
sarily and logically implied. The interval between them
seems to have been about 40,000 years. Now if we accept one
such unit, why not accept the previous ones also? After all,
the laws of nature work continuously: that was the principle
laid down by Sir Charles Lyell over a century ago. It is ob-
viously sensible to work from the known to the unknown:
if we are fairly sure that the crust did move once or twice,
and at a certain rate, then it is but a jump to accepting with-
out a qualm a thousand such movements in the long history
of the globe.
The further advantages inherent in the assumption of the
Alaskan pole, and the general evidence for it, may be briefly
summarized. It explains the cause of the warm Interglacial
Period in Europe, when lions and hippopotamuses and ele-
phants romped around in Britain and on the Continent (to
which Britain was then probably joined). It allows for the
Sangamon Interglacial in the eastern parts of the United
States and Canada. As between the two polar positions, in
Greenland and Alaska, we have an explanation of the length
of the Sangamon Interglacial. We may visualize it as a warm
period that began and ended at different times in different
parts of North America, and that was warmer in given areas
at certain times than at others. The speed of climatic changes
was slow enough to permit the gradual migration and adapta-
tion of species, and yet there were also abrupt, disastrous
changes due to the effects of volcanism, which, as we have
EARLIER DISPLACEMENTS OF CRUST 305
seen, could account for the widespread Pleistocene extinc-
tions.
Speaking of more specific evidences, if the Alaskan Penin-
sula were near the North Pole, this would have meant the
deglaciation of the Ross Sea and, indeed, of all that half of
Antarctica. What have the Ross Sea cores (Figure XI) to
say? Core N-4 shows deposition of nonglacial sediment from
110,000 to 130,000 years ago. This by itself provides some
confirmation. Core N-5 shows deposition of nonglacial sedi-
ment from 130,000 to 180,000 years ago, implying that either
the pole was situated in Alaska for a long time or else a still
earlier polar position was so situated as to give Antarctica
temperate conditions. Core N-g shows fine glacial sediment
from about 120,000 to about 200,000 years ago. This, too,
implies a climate warmer than the present, but the evidence
is, obviously, inconclusive. Only a great many more cores
from the same area can clarify these ambiguities.
As I have mentioned, with each step backward into the
past, the evidence decreases geometrically in quantity. The
available indications of a pole in Alaska amount to no more
than suggestions for research, but, in my opinion, they can-
not be disregarded on that account. It might be objected
that if Alaska was at the pole only 100,000 years ago, there
should be plentiful evidence of a continental glaciation in
Alaska. We must not be too easily impressed by this objec-
tion. In the first place, there is a possibility that many of the
evidences have been destroyed since that time by the glaciers
of the Wisconsin period, and by the present glaciers. Then,
there is the obvious possibility that evidences have been over-
looked or misinterpreted, as seems to have occurred in Brit-
ain. Finally, if widespread subsidence of land areas has oc-
curred in the North Atlantic, so may it have occurred in the
Pacific. Extensive evidence of a North Pacific land bridge
(not to be confused with a Behring Strait connection) has
been summarized by Dodson (115:373). How long Dodson's
land connection may have lasted is not known, but it could
conceivably have lasted until comparatively recent times.
306
EARTH'S SHIFTING CRUST
CORRELATION IN YEARS TOUT'S €8' I?1 8
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ACE DETERMINATIONS BY
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Fig. XI. Lithology of Core Samples, Ross Sea, Antarctica
EARLIER DISPLACEMENTS OF CRUST 307
A small amount of additional evidence for our assumed
sequence of climates in Alaska has come to light. Our assump-
tions call for a frigid climate in Alaska down to about 75,000
years ago, with a warming of the climate coinciding with the
refrigeration of the Atlantic as the polar position migrated
to Greenland. Then, about 25,000 or 30,000 years ago, the
climate was refrigerated (later than in eastern North Amer-
ica) as a consequence of the advance of the Wisconsin ice
sheet.
Karlstrom (247) has shown through radiocarbon dating
that the oldest glacial stage of the Wisconsin glacial period
in Alaska began not earlier than the Farmdale Advance in
Ohio, 25,000 years ago, and not later than 19,000 years ago.
This is in accord with our supposition that the glacial cli-
mate advanced from the east. Before this Alaskan glacial
stage, Karlstrom has an interglacial extending back an un-
certain distance. This, obviously, is, in terms of current
theory, in disaccord with the contemporary climatic trends
in the Atlantic. Before the interglacial period Karlstrom
notes evidence of a glaciation that he considers to be pre-
Wisconsin but post-Illinoisan. Since this glaciation was be-
yond the range of the radiocarbon method, he had to depend
upon the assumption of climatic control by the solar insola-
tion curve in order to estimate its date. He estimates that
this older glaciation was at least 47,000 but not more than
87,000 years ago. Presumably these dates mark the estimated
time of the end of the glaciation. Even though his basis of
calculation may not seem acceptable (for reasons already dis-
cussed), it is plain that his date is in pretty good accord with
our date for the Alaskan pole. No doubt it is based in part
on a lot of stratigraphic studies that prove the antiquity of
the glaciation, and at the same time show that it is younger
than the Illinoisan ice age.
This climatic reconstruction throws an interesting light on
a forgotten item of paleontological research that I chanced
upon in the Smithsonian Miscellaneous Collections for 1913.
It was entitled "Notice of the Occurrence of a Pleistocene
308 EARTH'S SHIFTING CRUST
Camel North of the Arctic Circle/' The author, James Wil-
liam Gidley, described the discovery in Alaska not only of
the camel remains but also of the remains of elephant and
of other animals, including the horse and bison. He then
remarks that the discovery "adds proof in support of the sup-
position that milder climatic conditions prevailed in Alaska
during probably the greater part of the Pleistocene period"
(173:1). We do not have to go all the way with Mr. Gidley.
But here indeed is evidence enough of the existence of
really temperate conditions very possibly in the very period
of time when the assumption of the Greenland pole calls for
them. A final consideration relating to the evidence for a
pole in Alaska is that this could have caused the Cordilleran
glaciation, which, according to Coleman, preceded the Lab-
rador and Keewatin ice sheets (87:10). It may be added also
that there is real support from fossil terrestrial magnetism
for the polar succession in Alaska and Greenland. The Jap-
anese geophysicist Akimoto and his colleagues have produced
magnetic evidence of the migration of the pole from north
of North Central Siberia, in the Arctic Ocean, across Alaska
to Greenland in the Pleistocene (418:11).
Thus the matter must be left, for the present. If it seems
to the reader that I have sometimes based too much on too
little data, and that I sometimes attribute too much signifi-
cance to isolated facts, I agree that I have probably commit-
ted this error at times. On the other hand, there is sometimes
a tendency to postpone any thinking, in the hope that the
necessity of revising basic principles may be removed by
additional facts.
6. The Remoter Past
Since, as I have mentioned, with every step backward into
time the evidence becomes thinner, it is hardly worth while
to attempt, at present, to solve the problem of the earlier
positions of the poles that would be required to explain the
EARLIER DISPLACEMENTS OF CRUST 309
climatic history of the Pleistocene. Eventually, perhaps, this
can be done. Much more practical questions remain to be
considered.
We must consider whether the rate of geological change
suggested for the last 130,000 years, by the evidence pre-
sented in this book, can be typical for the entire history of
the earth. It is plain from the cores that rapid change has
characterized the record for the Pleistocene. Radiocarbon
dating has established the fact that all the geological processes
of glacial growth and decay, precipitation and sedimentation,
were enormously accelerated during the Wisconsin ice age.
Emiliani has argued, as already mentioned, that all the ice
ages of the Pleistocene occurred in the last 300,000 years,
which implies a threefold increase in the velocity of geologi-
cal change, as compared with the older views. Studies of the
delta of the Mississippi River suggest numerous important
changes at short intervals (165, 276, 349). Blanchard has
shown that there were at least twelve major climatic changes
in the valley of the Somme since the first glaciation, accom-
panied by changes in sea levels, fauna and flora, and human
cultures. As already mentioned, he argues that only polar
change can explain this record (38).
For the older geological periods, there are a number of
lines of evidence that suggest rapid change. So insistently,
indeed, does this theme occur in the strata that Brooks, in
his Climate Through the Ages, refers to a 2i,ooo-year cycle
of climatic change which he believes operated through the
whole Eocene Period, or for about 15,000,000 years. His fig-
ure, of course, is only a rough average, and the intervals may
have been very unequal in length. With reference to a still
older period he remarks, "Alternations in the Cretaceous
of U.S.A. suggest a cycle that is estimated at 21,000 years,
but there are no annual layers" (52:108).
Irregularities in the cycle are indicated by another study
of Eocene beds covering about 5,000,000 to 8,000,000 years.
In this case annual varves were present, and they indicated
long-term changes at 23,000 and 50,000 years (52:108). Some
EARTH'S SHIFTING CRUST
scientists have attempted to explain these cycles as the result
of the earth's astronomical precession, but, in view of the
above-mentioned irregularities, the phenomena seem better
explained in terms of crust displacements.
Naturally, such frequent changes in climate have had pro-
found effects on the formation of sedimentary rocks, the
chief consequence, perhaps, being the thinness of the indi-
vidual strata. Very seldom can deposits be found that indi-
cate with any certainty the uninterrupted deposition of more
than a few thousand years. On the other hand, innumerable
cases of conditions interrupted after a few thousand years
can be proved. In addition to the evidence mentioned above,
Brooks, for example, refers to a great salt lake or inland sea
that existed in Europe in the Permian Period, and says:
The number of annual layers indicates that the salt lake existed
for some 10,000 years, after which the salt deposits were covered by a
layer of desert sand (521*5).
Wallace, too, refers to the evidence of sudden changes in
climate at short intervals, in his Island Life: ". . . the
numerous changes in the fossil remains from bed to bed only
a few feet and sometimes a few inches apart" (446:204).
Some of the best evidence is provided by coal seams, which
are ordinarily thin and interlayered with rock indicating
very different climatic conditions. There has developed a
considerable literature on the rate of coal formation, and
some recent experimentation has thrown light upon it.
Croll devoted considerable attention to the problem. He
estimated that it would take about 5,000 years for the forma-
tion of one yard (or about a meter) of coal (91:429), and
came to the conclusion that the periods of coal formation
between changes in climate were about 10,000 years long. It
is obvious that any changes that replaced conditions required
for coal formation by conditions suitable for the formation
of sedimentary deposits beneath the sea (for Croll points out
that rock strata between the coal strata are usually of marine
origin) (91:424) were indeed radical changes, taking place in
EARLIER DISPLACEMENTS OF CRUST Jll
short periods of time. Another writer, Otto Stutzer, after
very careful calculation, concluded that a Pittsburgh coal
bed seven feet thick could have been formed in no more
than 2,100 years (407).
In view of all this evidence, we must not be too much im-
pressed by the very thick layers of rock that are occasionally
found. Croll, who was a sound geologist, even if his theory
about ice ages was not accepted, pointed out that
. . . The thickness of a deposit will depend upon a great many
circumstances, such as whether the deposition took place near to land
or far away in the deep recesses of the ocean, whether it occurred at
the mouth of a great river or along the sea-shore, or at a time when
the sea-bottom was rising, subsiding or remaining stationary. Stratified
formations 10,000 feet in thickness, for example, may under some
conditions, have been formed in as many years, while under other
conditions it may have required as many centuries (91:338).
It is worth noting that at a number of points the evidence
for great and frequent changes in the earth's climatic condi-
tions is linked with evidence of structural changes in the
earth's crust, that is, with changes in the elevation of lands,
and in the distribution of land and sea. Croll remarked:
... It is worthy of notice that the stratified beds between the coal
seams are of marine and not of lacustrine origin. ... If, for example,
there are six coal seams, one above another, this proves that the land
must have been at least six times below and six times above sea-level
(91:424).
Coleman has emphasized the frequent association of
abrupt breaks in the continuity of the strata with extreme
changes of elevation above or below sea level. In discussing
the Permo-Carboniferous period in India, he says:
There are the usual cold climate fern leaves in these beds, and
above them, without an apparent break, come the Productus lime-
stones with marine fossils (87:102).
Now, it seems altogether reasonable to suppose that if
changes of climate were associated with changes of elevation
in these different kinds of cases, then the two may have oc-
EARTH'S SHIFTING CRUST
curred at the same tempo, and have proceeded from the
same cause. The hypothesis of periodical shifts of the earth's
crust provides both the link and the cause.
An interesting study of repeating geological cycles in a very
remote period has been completed by Weller (451). He deals
with the so-called "Pennsylvanian" period several hundred
million years ago, which had a span of between 35 and 50
million years. He points out that in the study of this period
numerous examples have been observed of the deposition
of different kinds of sedimentary beds in the same order, at
irregular intervals of time. The changes in the composition
of the beds imply changes both in climate and in the eleva-
tion of the areas above sea level. The cycles are not just local,
but can be traced over wide areas (451:110). Furthermore,
each complete cycle represents an advance, retreat, and re-
advance of the sea. Weller accounts for the cycles by dias-
trophism— that is, by some sort of upheaval in the earth,
some activity within the earth's body— but is not able to
specify its nature. He recognizes about 42 cycles during the
period, with each cycle having a duration of about 400,000
years.
These cycles would appear at first glance to be consider-
ably longer than those that might result from crust displace-
ments. However, there are a number of factors that tend to
lessen the apparent difference between them. First, Weller
points out that discontinuities in the deposits he is discussing
are far more numerous than is generally supposed (451:99-
101). This means that a part of the record is missing. Then,
we must remember that a complete cycle, involving the re-
treat and the advance of the sea (probably in a number of
stages), would call for several, perhaps quite a few, move-
ments of the crust. At any one point on the earth's surface,
several movements might be required to bring the sea level
to its lowest point, and several more to bring it to its highest
point. We have already discussed this question (Chapter IV).
Moreover, Weller points out that in each of his cycles deposi-
tion has been interrupted two different times, thus reducing
EARLIER DISPLACEMENTS OF CRUST
the average length of the subdivisions of the cycle to periods
of the order of 75,000 to 250,000 years. But it must be re-
membered that we have only averages; the cycles differ
greatly and their subdivisions also differ greatly in length.
When we consider the fact that the intervals and directions
of crust displacements are necessarily irregular, there appears
to be a very good agreement between our theory and the
facts of the Pennsylvanian cycles. At least, it will hardly be
denied that the theory offers the first possibility of under-
standing the cycles. Moreover, if our recent experience of the
shortening of our estimates of geological time in the Pleisto-
cene is a valid basis for extrapolating to earlier periods, it
may well be that geologists have exaggerated the length of
the Pennsylvanian Period, and that Weller has consequently
attributed too great an average duration to his cycles. It
appears, therefore, that crust displacements may have been
occurring through the whole of one of the major subdivisions
of the Paleozoic Era.
It is impossible, however, in the present state of the evi-
dence, to say that displacements of the crust have been going
on uninterruptedly all through geological history. It may be
that there have been times of quiet, when, for one reason or
another, great icecaps failed to develop. The important thing
at the moment is that investigators should be willing to un-
dertake further inquiry without preconceptions based on
outmoded ideas of gradual change. We may note a serious
warning against this bias uttered by no less an authority than
Sir Charles Lyell, the greatest geologist of the first half of the
nineteenth century, and the father of gradualism in geology.
In the course of a discussion of some evidence of recent fold-
ing of rock strata on the Danish island of Moen, he remarked:
It is impossible to behold such effects of reiterated earth move-
ments, all of post-Tertiary date, without reflecting that, but for the
accidental presence of the stratified drift, all of which might easily,
where there has been so much denudation, have been lacking, even
if it had once existed, we might have referred the verticality and
flexures and faults of the rocks to an ancient period, such as the era
314 EARTH'S SHIFTING CRUST
between the chalk with flints and the Maestricht chalk, or to the
time of the latter formation, or to the Eocene, or Miocene or older
Pliocene eras. . . . Hence we may be permitted to suspect that in
some other regions, where we have no such means at our command
for testing the exact date of certain movements, the time of their oc-
currence may be far more modern than we usually suppose (281:
393-94)-
And let us also recall the following words of the greatest geol-
ogist of the second half of the nineteenth century, Eduard
Suess:
The enthusiasm with which the little polyp building up the coral
reef, and the raindrop hollowing out the stone, have been contem-
plated, has, I fear, introduced into the consideration of important
questions concerning the history of the earth a certain element of
geological quietism— derived from the peaceable commonplaceness of
everyday life— an element which by no means contributes to a just
conception of those phenomena which have been and still are of the
first consequence in fashioning the face of the earth.
The convulsions which have affected certain parts of the earth's
crust, with a frequency far greater than was until recently supposed,
show clearly enough how one-sided this point of view is. The earth-
quakes of today are but faint reminiscences of those telluric move-
ments to which the structure of almost every mountain range bears
witness. Numerous examples of great mountain chains suggest by
their structure the possibility, and even in some cases the probability,
of the occasional intervention in the course of great geological eras
of processes of episodal disturbances of such indescribable and over-
whelming violence, that the imagination refuses to follow the under-
standing and to complete the picture of which the outlines are
furnished by observations of fact (408:!, 17-18).
The great work from which the foregoing statement was
taken is entitled The Face of the Earth. The prospect that
unfolds before us, as we contemplate the possibility that total
displacements of the earth's crust have been a feature of geo-
logical history since the formation of the crust itself, is noth-
ing less than the discovery of the formative force, of the
shaping factor, that has been responsible not only for ice
ages, not only for the mountain ranges, but even possibly for
the very history of the continents, and for all the funda-
mental features of the face of the earth.
X : LIFE
In the preceding chapters we have reviewed a mass of evi-
dence that suggests displacements of the earth's crust, at
comparatively short intervals, during the earth's history. We
shall now see that this assumption throws some light on the
process of evolution.
/. The Cause of Evolution
A century ago, in the Origin of Species, Darwin suggested
natural selection as the mechanism to account for evolution.
The combination of the occurrence of natural variations
with elimination of the unfit individuals in the competitive
struggle for existence helped to explain a process of un-
ending, gradual change in the forms of life. Darwin did not
consider that this was the whole answer. He admitted, for
example, that he could not explain the numerous instances
of the world-wide extinction of many forms of life simultane-
ously, especially in those cases where, apparently, there were
no competitors and no successors to the extinct forms. Biolo-
gists today are in agreement that evolution has occurred, but
they also feel that the process has not been satisfactorily ex-
plained. Thus Dr. Barghoorn, of Harvard, has recently re-
ferred to "our limited understanding of the actual causes of
evolution," while quoting Dr. George Gaylord Simpson,
author of the widely read Meaning of Evolution, as remark-
ing, ". . . search for the cause of evolution has been aban-
doned" (375:238). There is a tendency at the present time
for specialists to recognize a large number of interacting fac-
tors that may, together, conceivably account for evolution,
though their relative importance is not agreed upon. This
situation does not exclude the possibility that the confusion
316 EARTH'S SHIFTING CRUST
may, indeed, arise because one factor is still missing: a factor
which, when added, will bring the others into proper focus.
2. The Problem of Time
While no biologists since Darwin's time have questioned the
basic fact of evolution, numerous difficulties have developed
with natural selection. In the first place, while Darwin could
present evidence of changes produced in varieties of plants
and animals by artificial selective breeding, he was not able
to show how, even under artificial conditions, such changes
could lead to the establishment of new species. Recently,
some progress may have been made in solving this problem,
but by the end of the nineteenth century, Darwin's explana-
tion of the mechanism of evolution had been largely aban-
doned. Natural selection had come to be considered, by
many biologists, as chiefly a negative factor, capable of elimi-
nating unadapted variations but not of producing new
species.
Around the turn of the century the attention of evolution-
ists was turned to mutation, the sudden change in hereditary
characteristics produced by an alteration of the basic genetic
factors, genes and chromosomes. One of the early mutation-
ists, Hugo de Vries, believed that a large-scale mutation
might produce a new kind of plant or animal in a single
step (115:96). Many evolutionists then adopted mutation,
and gave up natural selection as the explanation of evolution.
This did not, however, end the controversy. A neo-Dar-
winian school, clinging to natural selection, raised damaging
objections to the theory of evolution through massive muta-
tions. They insisted, for one thing, that different plants or
animals differed by a great many minor traits, rather than
by a few major ones. This would mean that a great many
mutations would be required, and that these mutations
would have to take place in the same individual, or in the
same line of descent. The fact that mutation is apparently
LIFE 317
an entirely accidental process rendered the mathematical
chances against the coincidence of many mutations in one
individual or in one line o£ individuals completely over-
whelming.
But this was by no means the only difficulty. The anti-
mutationists could argue that since mutations were purely
accidental changes in the hereditary factors, and did not
occur in response to needs created by the environment, most
mutations would be positively harmful, or at least negative,
and would have no effect on the adaptation of the organism
to its environment. Only a chance mutation now and then
could help an organism to survive. Mutationists were unable
to show the existence of any principle by which mutations
would be adaptive, that is, brought about as a part of an
effort of an organism to adapt to the environment. Some
recent experiments indicate that such adaptive mutation
may occur, perhaps under special and rare conditions, but
it still cannot be shown that adaptation by mutation has been
an important factor in evolution.
The mutationists did establish, of course, that minor muta-
tions were of frequent occurrence, and might even be in-
duced artificially; therefore, evolutionists accepted them, but
they recognized them as just another way of accounting for
the occurrence of variations. The law of natural selection
would still be required, in order to eliminate the harmful
mutations, which would constitute the great majority of all
mutations. For a while it seemed that, in this way, the basic
question of evolution was answered.
It soon appeared that this was very far from being the
case. The acceptance of mutations by the Darwinians as a
factor in evolution did not solve the problem. It became
clear, as time passed, that a major difficulty remained. Atten-
tion was concentrated on the rate at which mutation and
natural selection could be effective in changing life forms.
Mathematical studies showed that such changes would take
place, according to the theory, at rates so slow that even long
318 EARTH'S SHIFTING CRUST
geological eras would provide insufficient time for evolution.
Professor Dodson wrote:
In nature, neither mutation nor selection will ordinarily occur
alone, and so the two will act simultaneously, perhaps in the same
direction, perhaps in opposite directions. . . . Most frequently, selec-
tion will work against mutation, as the majority of possible mutations
are deleterious. This will result in very slow change, if any. . . .
(115:298).
He emphasized:
It appears that it is extremely difficult for mild selection pressures,
unaided by any other factor, to establish a new dominant gene in a
species. . . . (115:298).
By "mild selection pressure/' Dodson means those condi-
tions of competition between life forms pointed out by Dar-
win, that is, the competition that goes on at all times. What
he suggests here is that some more drastic influence must
have operated to produce evolutionary change.
After discussing Haldane's mathematical calculations indi-
cating the astronomical numbers of generations that might
be required to change a plant or animal under the influence
of mild selection pressures, Dodson quotes Dobzhansky (the
leader of the neo-Darwinian school) on their implications:
. . . The number of generations needed for the change may, how-
ever, be so tremendous that the efficiency of selection alone as an
evolutionary agent may be open to doubt, and this even if time on a
geological scale is involved (115:298).
Thus the problem is clearly posed: it is the problem of
time. It is necessary to find some way of explaining how
natural selection can have operated at a sufficiently rapid
rate to account for evolution. A factor of acceleration is re-
quired.
Some writers, when they saw that evolution could not be
explained even with the enormous amounts of time available
under the current concepts of the lengths of the geological
periods, felt compelled to revert to mystical explanations.
Writers such as du Noiiy (119) concluded that evolution was
LIFE
totally inconceivable unless its course had been indicated in
advance, by the reigning influence of cosmic purpose. For
these writers, the end or final purpose of evolution must be
the active controlling force of the whole process. The process,
at basis, could be understood only as the direct effect and
evidence of the will of God.
Another solution was proposed by Richard Goldschmidt,
who became the leader of the anti-Darwinians. He renewed
the emphasis on major or macromutations. As Dodson
puts it:
. . . Goldschmidt believes that the neoDarwinian theory places
too great a burden upon natural selection, and hence that the work
of selection must be shortened by some other process, namely sys-
tematic mutation (115:299).
By "systematic mutation* ' is meant a mutation that changes
not merely an individual trait of an organism but a whole
complex of traits, that is, that changes a basic principle of
the biological system. The great advantage of Goldschmidt's
theory is that it may greatly reduce the number of "genes"
required to account for the traits of a single individual.
Under present concepts of genetics, for example, from 5,000
to 15,000 "genes" may be called for to account for all the
traits of the fruit fly, Drosophila melanogaster, while as many
as 120,000 may be required for man (115:245). The gene it-
self, of course, since it has never been identified under the
microscope, and since its structure and mode of functioning
are entirely unknown, must still be classified as a useful scien-
tific assumption, rather than as a verified entity. The present
state of gene theory is roughly analogous to the state of
atomic theory before the development of subatomic physics.
Then the atomic theory was accepted because it worked in
practice, but nobody knew what an atom was. Today, we
know only that some sort of unit like a gene seems necessary.
The majority of writers on evolution today seem to feel
that Goldschmidt's specific arguments for macromutations
have been refuted. I can contribute no opinion on this tech-
nical question. But, from my point of view, the most signifi-
320 EARTH'S SHIFTING CRUST
cant thing about the Goldschmidt theory is that he produced
it in an effort to gain time for the process of evolution, to
accelerate it, so that the amount of evolutionary change in
life forms could be brought into rough agreement with the
available amount of geological time. The rejection of his
theory, if the rejection is indeed based upon sound considera-
tions, means that another factor must be found to account
for the tempo of evolution.
3. Climate and Evolution
Evolutionists, in general, agree that climatic change must
have had a powerful influence on evolution. Geologists have,
as I have pointed out, found a correspondence between
periods of climatic change and changes in the forms of life.
It is evident that as long as the general environment remains
roughly the same, there can be only gentle selection pressures
such as, apparently, are inadequate to account for evolution.
With static environmental conditions, forms of life may con-
tinue virtually unchanged for tens or hundreds of millions
of years. There are any number of organisms living today
whose very similar ancestors lived in remote geological
periods. To name merely a few, there is the newly discovered
coelacanth, a fish whose ancestors, one hundred or more
million years ago, looked as he does today; the recently dis-
covered Dawn Redwood, found growing in China, after hav-
ing been regarded as extinct since its close relatives disap-
peared in Alaska about 20,000,000 years ago; the sphenodon,
a reptile of New Zealand, whose ancestors, very closely re-
sembling himself, were contemporaries of Tyrannosaurus
rex; horseshoe crabs, whose time span may amount to half a
billion years; palm trees, whose age has just been "jumped"
another 10,000,000 years (261); sharks; scorpions, and so on.
Sanderson has pointed out that "living fossils" are simply too
numerous to list (365). We can take it that, if external condi-
tions are stable, or if animals and plants can migrate around
LIFE 321
to find the conditions they are used to, they may continue to
exist indefinitely.
At the same time, it is equally true that any kind of animal
or plant may succumb, in the course of the usual and con-
tinuous competition between life forms, and the local or
transitory climatic variations that are always occurring. It
would distort the picture to forget this fact. Furthermore,
recent studies have shown that new varieties of plants and
animals can appear within very short periods of time, on the
order of a century or less, if they live in conditions of isola-
tion (115:365). But these rapidly produced varieties are not
the same, of course, as established species.
A factor which, undeniably, must produce pressure for
profound change in the forms of life is major climatic change.
Clearly, this will apply what evolutionists call "strong selec-
tion pressure." In this case life forms will have but three
alternatives: to migrate, to adapt, or to die. Geologists and
biologists have never denied the truth of this: Coleman, for
example, recognized the importance of the glacial periods in
"hastening and intensifying" the process of evolution (87:62).
Lull recognizes the importance of basic climatic change,
thus:
. . . For changes of climate react directly upon plant life, and
hence both directly and indirectly upon that of animals, while re-
striction or amplification of habitat and the severance and formation
of land-bridges provide the essential isolation, or by the introduction
of new forms increase competition, both of which stimulate evolution-
ary progress (278:84).
The problem has been, until now, that major climatic
changes, and concomitant changes in the distribution of land
and sea, could not be explained by any acceptable theory.
They were inexplicable events in themselves; their coinci-
dence in time was inexplicable. Even more serious, they were
assumed to have happened only at such extremely long inter-
vals that the total number of such major climatic "revolu-
tions" was too small to account for more than a very insig-
nificant portion of evolutionary history.
322 EARTH'S SHIFTING CRUST
To recapitulate what has already been said, if drastic cli-
matic and geographical change is the most obvious factor
to which to look for changes in life forms, then it is to the
acceleration of that factor that we must look for the accelera-
tion of evolution. In the previous chapters we have been led
again and again by the force of the evidence to the concept
of displacements of the earth's crust. There is no reasonable
doubt as to the effect that such displacements, at relatively
short intervals, would have on the tempo of evolution. They
could not fail enormously to accelerate the several aspects of
the evolutionary process. Let us now examine some of these
special aspects in more detail.
Wright has pointed out that the rate of evolutionary
change may have been accelerated at various times through
the mass transformation of one kind of plant or animal into
another (115:314). This requires that all over the area of
distribution of the life form in question there must be strong
pressure for change in the same direction. This means that
similar new varieties would appear simultaneously and inde-
pendently in countless localities or that well-adapted new
varieties would spread and become established rapidly. Quite
obviously this would tend to accelerate evolution.
But how would such mass transformation be brought
about? It could only result from profound transformation of
the environment. The required change would have to be
general and would have to tend in the same direction for a
considerable period of time. No short-range fluctuations and,
above all, no merely local climatic changes would suffice. A
displacement of the crust appears to meet all these require-
ments. For a period of many thousands of years, some areas,
moving toward the equator, would be growing warmer;
others, moving toward the poles, would be growing colder.
In the areas moving toward the equator (not necessarily
reaching the equator, however, or even the tropics) the in-
crease of sunlight would mean more luxuriant life condi-
tions; for many species this might mean increased food
supplies and an extended distribution. It would also be likely
LIFE 323
to mean increased competition with other forms. Many
effects would depend upon whether the displacement carried
the area in question into the wet tropics or into the dry horse
latitudes, or merely from an arctic into a temperate climate.
Meanwhile, of course, in areas displaced poleward, opposite
trends would exist; here the forms of life would have to adapt
to diminishing light, to increased cold, to decreased food
supplies.
What is important is that these changes of climate would
apply over great areas of the earth. In one movement of the
crust, two opposite quarters of the earth's surface would be
moving equatorward while two others were moving pole-
ward. Thus the climatic changes would be in the same direc-
tion over very great areas: the entire distribution, perhaps,
of many plants and animals. Mass transformation of life
forms might therefore be expected to occur; not mass trans-
formations of all life forms, of course, but merely one or two
short steps in the mass transformation of one or a few kinds
of plants or animals. New varieties might be established in
great numbers, during a single movement of the crust; but
by this I do not mean to imply that many new "species"
would be. The latter may be the end results of a considerable
number of displacements of the crust. I hope that the reader
will not ask me to define "species." In this book I use the
term simply to denote forms of life that are reasonably dis-
tinct and relatively permanent.
We must remember that the different areas of the earth's
surface would be unequally shifted in a crust displacement.
I have explained (Introduction) that the amount of the dis-
placement would depend on whether an area was near to, or
distant from, the meridian of displacement. Selection pres-
sures would vary accordingly.
Since we consider displacements to have taken place in
short periods of the order of 10 or 20 thousand years, it seems
likely that most plants and animals in areas radically dis-
placed by a given movement would be unlikely to succeed
in adapting. Some would migrate into areas having climates
324 EARTH'S SHIFTING CRUST
similar to their accustomed climates. Some would disappear.
Some would develop varieties adapted to changed conditions.
Even though there would be no wholesale creation of new
plants and animals, the age-long process of change would
have received an acceleration.
Another important, generally accepted requirement for
evolution, as already suggested, besides climatic change, is geo-
graphical isolation to permit the development of new vari-
eties. Geneticists agree that the larger the population of a
given sort of plant or animal, the harder it is for a new variety
to get established, because crossbreeding tends to destroy the
new variety. If, however, populations are cut off from each
other, and are reduced in numbers, a new variant has a much
better chance to become dominant, and establish itself as a
variety in that locality. As already pointed out, crust dis-
placements can account for the alternation of conditions of
geographical isolation and intercommunication at the tempo
required to account for evolution, because they can account
for rapid, recurrent changes of sea level. Let us now visualize
the consequences of a displacement of the crust resulting in a
subsidence of a continental area displaced equatorwards. Let
us suppose a moderate subsidence of a few hundred feet only,
over a period of a few thousand years. The result, of course,
would be the deep intrusion of the sea into the continent.
The sea would invade valleys, cutting off one part of the
mainland from another, and creating islands and island
groups. Many populations of the same kind of plant or ani-
mal would thus be isolated, and left for many thousands of
years to develop and establish new variant forms.
Let us suppose many new varieties to have become estab-
lished in the islands, and in areas of the mainland separated
from each other by tongues of the sea. The next requirement
of evolution is that these new varieties should be brought
into competition and that the best adapted of them should
be disseminated into more varied habitats. This might be
brought about by a new movement of the crust, such as
would displace this area poleward. The area will now be up-
LIFE .325
lifted, the sea will withdraw, and the life forms formerly
isolated will mingle and enter a phase of competition.
The situation that compels the adaptation of the forms of
life to colder, drier climates (poleward displacement) also will
adapt the forms of life to higher elevations, to mountain
heights. Thus, if we consider all the effects of crust displace-
ment, both toward the equator and toward the poles, we can
see that crust displacement constitutes the most powerful
engine imaginable for forcing life forms to adapt to all
possible habitats.
-/. The Distribution of Species
Another important question is the problem of the origin of
the present and past distribution of species over the face of
the earth. Darwin and Wallace attempted to explain the
numerous difficulties in this field, but their explanations
have, in general, become less and less satisfactory with the
passing years. These are the questions:
a. How did certain species cross wide oceans to become
established on different continents?
b. What accounts for the richness of some islands, and the
impoverishment of others, with respect to their fauna and
flora?
c. How did many kinds of animals and plants get dis-
tributed from the north temperate to the south temperate
zones, or from one polar zone to another, across the tropics?
d. Why are certain species of fresh-water fish, inhabiting
the lakes and rivers of Europe, also found in the lakes and
rivers of North America?
Some of the answers to these puzzling questions will al-
ready be clear from what has been said about land bridges.
Land bridges, or sunken continents, are obviously necessary
to explain many of these distributions between continents
and between continents and islands. Sunken continents have
already been discussed (Chapter V). Here I would like to
526 EARTH'S SHIFTING CRUST
discuss the situation that confronts us if we are not allowed
to postulate sunken continents or land bridges.
If we cannot find an acceptable mechanism to account for
the creation and destruction of land bridges (or sunken conti-
nents) we are forced back upon the ingenious ' 'sweepstakes"
idea, which has been much overworked, as an explanation
of the distribution of species. This idea arose because it was
observed that sea birds, or migratory birds, may carry the
seeds of plants or the eggs of insects from continent to conti-
nent, and that some species manage to cross, by chance,
bodies of water on floating objects such as logs or even ice.
By conveniently ignoring about nine tenths of the evidence,
this idea has been given considerable importance. Even
though many species have migrated in this way, the idea is no
substitute for land bridges. Nor, it may be added, is one land
bridge, at Behring Strait, able to do the work of explaining
the infinite number of plant and animal migrations in all
climatic zones in all geological periods. Many land bridges
are required, and for these an explanation is necessary. The
theory presented in this book, however, can explain the crea-
tion and destruction of land bridges (and sunken continents),
and therefore it can explain the distribution of species across
large bodies of water.
The impoverishment of certain island faunas and floras as
compared with others may be understood as follows. Some
of these islands may have rich faunas and floras because, in
recent time, they have had land connections with adjacent
continents. This would be true of the Philippines, of Java,
of Sumatra, and of numerous other islands in that area,
whose former continental connections with either Asia or
Australia have been argued for by Wallace (446) and others.
It is not a question of showing that the species in these
islands came from the continents; it is simply true that there
were land connections, and that the species wandered back
and forth; we don't know where they originated.
An island like Java can have a rich fauna and flora not only
because of having had rather recent connections with the
LIFE 327
continent of Asia, but also because it is mountainous. This
makes it possible, supposing at some time an equatorward
displacement of the island into a warmer latitude, for tem-
perate climate species to ascend into the mountains and so
survive. Such variety of climatic conditions, due to differ-
ences of altitude of different parts of the island, would favor
the preservation of a rich flora and fauna.
Let us contrast with Java the situation of a small island or
island group, such as the Bermudas, the Azores, or the Ca-
naries, where, in general, we find the life forms to be
impoverished. These islands, often far from the nearest
continent, may have been separated from them, of course, for
long periods of time. Now let us suppose one of them, say
the Azores, to be displaced through about 2,000 miles of
latitude in one movement of the crust, in either direction.
Where will the indigenous species go? Obviously, there will
be no refuge for them; therefore, many of them will succumb.
Subsequently, the sea will be an effective barrier to the re-
population of the islands from the mainland.
As to the distribution of life forms across the climatic
zones, referred to as "bipolar mirrorism," Darwin proposed
an explanation in Chapter 12 of the Origin of Species that
can no longer be accepted. He supposed, % first, that glacial
periods alternated in the Northern and Southern Hemi-
spheres. This idea has long since been given up. Then, Dar-
win reasoned that when there was an ice age in the Northern
Hemisphere, the climatic zones would be displaced south-
ward, and the temperate zone species would migrate south-
ward. When that ice age ended, and the climate warmed up,
the temperate species that had migrated southward would
now ascend into the mountains, where they would survive,
in the tropic zone. There are, of course, mountains in the
tropics high enough to be snow-capped the year around;
on these even arctic plants might exist.
The next step, according to Darwin, would be the onset
of an ice age in the Southern Hemisphere. Now the tempera-
ture in the southern tropics would fall, and become temper-
328 EARTH'S SHIFTING CRUST
ate, and the temperate species wcmld descend from their
mountains and migrate across the valleys southward to the
south temperate zone. In this way the migration of the species
from the northern to the southern temperate zone would
be accomplished.
Now this idea of the species clambering up and down the
mountainsides in response to the changing weather is a good
one, and gives us one key to the problem. Where Darwin
went wrong was in his alternating ice age theory; he could
hardly be blamed, in view of the prevailing ignorance about
ice ages. Darwin, of course, lived at a time when people were
first getting used to the idea of ice ages. But if Darwin was
wrong, if ice ages do not regularly alternate in the Northern
and Southern Hemispheres, how do we explain bipolar
mirrorism? For some decades now, glaciologists have been
holding grimly to the theory that ice ages were always simul-
taneous in the two hemispheres. In maintaining this view,
they have ignored the fact that they have made mincemeat
of Darwin's explanation of bipolar mirrorism. But this does
not concern them. They are concerned with explaining ice
ages, not with the distribution of species. They have sug-
gested no alternative explanation for the migration of species
across the climatjc zones. Instead, they have constructed a
theory that puts the migration of species, and even the sur-
vival of tropical species, into the realm of sheer impossibility.
They insist, we remember, that the temperature of the
whole earth was simultaneously lowered in glacial periods.
We have seen that at various times in the past great conti-
nental icecaps have existed at sea level within the tropics,
and even on the equator itself. I have already pointed out
that if the world temperature had been lowered enough to
permit a continental icecap in the Congo, there would have
been no place of refuge for tropical species of plants and
animals. Nowhere along the circle of the equator around the
earth would any tropical species have survived. This would
be equally true of land and sea forms of life.
Bipolar mirrorism, however, presents no problems if we
LIFE 329
reconsider it in terms of displacements of the crust. One
movement, let us suppose, takes the Rocky Mountains 2,000
miles to the south. The species climb higher. Later, in a series
of movements of the crust (not always, of course, in the same
direction), the Rockies finally end up south of the equator,
in a temperate climate. Now the species climb down, and
occupy the temperate valleys of the Southern Hemisphere.
The mountain chain has functioned as a ferryboat, simply
transporting species back and forth.
At this point it is interesting to reflect on how useful it is
to have these high mountain ranges. A low mountain range
would never do. It could never ferry a load of species across
the tropical zone.
5. The Periods of Revolutionary Change in Life Forms
The reader may have gained the impression that, while cer-
tain aspects of evolution have escaped satisfactory explana-
tion, at least the process itself has continued evenly through
all time. To this reader it may come as a shock, as it did to
me, to learn that this is not at all the case. There have been
remarkable variations in the rate of evolution. For long
periods it has marked time, and then some force, hitherto
unidentified, has initiated a phase of rapid change, a revolu-
tion changing so many forms of plant and animal life as to
alter the general complexion of life on the earth. All paleon-
tologists appear to agree on this point. Dr. Simpson uses the
term "Virenzperiod" to define the periods of rapid change.
Others refer to "explosive" phases of evolution or to "quan-
tum evolution." It must be understood that development
during these periods is rapid only relatively; new forms are
still not created overnight.
One phenomenon that frequently occurs during these
periods is termed "adaptive radiation." This is a kind of ex-
plosion in which one form (or species) rapidly gives rise to
dozens, scores, or even hundreds of new forms apparently at
330 EARTH'S SHIFTING CRUST
one and the same time. How is this phenomenon accounted
for?
We must distinguish between the biological process and
the circumstances that cause it to occur. The process is easily
explained. Let us suppose that a form of plant or animal is
widely spread over a considerable area. Its total population
may include some millions of individuals; over its whole
distribution there will be local variations in the environ-
ment, and consequently there will be selection pressures
operating simultaneously but in different directions on differ-
ent parts of the population in different habitats. New vari-
eties of the plant or animal will tend to appear to take
advantage of special opportunities offered by particular local
environments. This sort of thing is always going on, but it
does not, by itself, produce explosions of adaptive radiation,
Something more is required. Normally, a new variety of
any form has to compete with other forms already in posses-
sion of the necessary supplies of food, light, and water. The
situation that has the particular combination of these things
required by a given plant or animal is referred to as its life,
or ecological, niche. Naturally, if this niche is already effec-
tively occupied the spread of the new variety is restricted,
As an analogy, think of a garden in which you have set out
one hundred expensive strawberry plants of a totally new
variety, just before being called away for two months on
urgent business requiring your presence in a foreign country
What now happens? Weeds immediately take over the niche
you had hoped to preserve (artificially) for the spread of the
strawberry plants. Their spread is restricted, and their sur-
vival may be threatened.
In nature what seems to be required to permit the ver)
rapid dissemination of many new variant forms of the orig
inal plant or animal is an absence of competition. Empty life
niches are required. The question is, How is an empty life
niche produced? Occasionally, of course, it may have beer
there from the beginning; it may never have been occupied
because, presumably, there never was any form of life thai
LIFE 331
could utilize it, but after two billion or more years of evolu-
tion, such primeval biological vacuums are few indeed. Life
niches have, in general, been very well occupied for a very
long time. Something is required, therefore, to empty them.
This is where our theory comes in. The effects of a dis-
placement can be visualized in two stages. In the first, a
movement of a large continental area through many degrees
of latitude might well cause a very general extermination
of the inhabitants. We have seen how, in several instances,
this occurred during the late Pleistocene (Chapter VIII).
The consequence of the extermination of many kinds of
plants and animals (which is not to say their extinction, for
many of them might survive in other areas) would be to leave
their life niches empty.
The second stage, initiated by a new movement of the
crust, would be marked by the opening up of avenues for the
immigration of life forms from other land areas. Life forms
entering the continent would now enjoy a field day. They
would multiply; they would occupy rapidly a tremendous
area and all manner of habitats; they would produce variant
forms, and the variant forms would occupy appropriate
niches. Thus explosive evolution would take place. The new
forms need not always be immigrants; they could equally
well be local survivors of the period of depopulation, of the
displacement, who had somehow managed to hold their own
under unfavorable conditions. It seems highly probable,
indeed, that displacements of the earth's crust are the ex-
planation of explosive evolution.
We have already made mention of the fact that an interrela-
tionship between the revolutionary periods in evolution and
the critical phases of change in other geological areas has
been noted by many observers. Lull, for example, says,
. . . There are times of quickening, the expression points of evo-
lution, which are almost invariably coincident with some great geolog-
ical change, and the correspondence is so exact and so frequent that
the laws of chance may not be invoked as an explanation (278:687).
332 EARTH'S SHIFTING CRUST
Umbgrove mentions two specific examples of this phe-
nomenon:
The most important point of all, as far as we are concerned, is
that the two major periods of strong differentiation of plant life
correspond with two major periods of mountain-building and glacia-
tion of the Upper Paleozoic and Pleistocene (429:292).
The same thing is described by Professor Erling Dorf, of
Princeton (349:575-91). We need not take too seriously the
small number of turning points mentioned by them for the
reason that everything, after all, is relative. The turning
points mentioned by Umbgrove might turn out to have been,
in some respects, the most important turning points in the
history of life, and yet there may have been a hundred lesser,
but still very important, turning points.
Geologists who have sought an explanation of the rela-
tionship between biological and geological change have, in
some cases, favored the idea that geological change, such as
the formation of new mountain ranges, might have caused
both ice ages and biological change. We have seen that this
will not account for ice ages. We have also seen that geolo-
gists now generally admit their failure to explain mountain
building. It is unsatisfactory to attempt to explain the known
by the unknown; it will not do to drag in mountain build-
ing as the cause of evolution, when the former also is
unexplained.
Displacements of the earth's crust appear to be the con-
necting link between these different processes: they explain,
at one and the same time, ice ages, mountain formation, and
the significant turning points of evolution.
6. The Extinction of Species
It has already been shown (Chapter VIII) that our theory can
provide an explanation for the extinction of species. Some
further discussion of this problem is, however, required.
It has been suggested that the history of any particular
LIFE 333
species can be compared with the life of an individual, with
its phases of youth, maturity, and old age. Thus, the ex-
plosive period is the youth of a species, the period of quiet
and prosperous enjoyment of its life niche is maturity, and
its degenerative phase is its old age. Finally, extinction re-
sults from the exhaustion of the vital force of the species.
This theory assumes an innate cause, and a natural order for
the succession of the phases.
This idea has been widely disseminated, and in one form
or another it has served to confuse all the issues and obscure
the known facts. It is one more of those philosophical abstrac-
tions that people resort to who come up against an unsolved
problem and cannot stand the psychological tension of per-
severing in the search for truth. It is important that the
essentials of this matter should be made clear.
In the first place, the idea that a species is analogous to an
individual, and must go through similar phases, is a modern
revival of the Scholastic logic of the Middle Ages, like the
microcosm-macrocosm analogy (according to which some
people have recently argued that since planets are satellites
of the sun, and electrons are satellites of the nucleus of the
atom, then planets are exactly like electrons, and must obey
the same laws of physics). The alleged vital force, which is
supposed to set a preordained limit to the life of a species,
completely escapes scientific observation and experiment.
It is not only a mere assumption, it is also an unjustified
assumption.
The facts of paleontology do not agree with the analogy of
the life phases of a species with that of an individual. In very
many cases the same phase may be repeated several times in
the life of a species, and other phases may be omitted alto-
gether, as we shall see below. For this reason the theory
brings caustic comment from Dr. Simpson. After discussing
the two phases of adaptive radiation (youth) and "intrazonal
adaptation" (establishment in a stable but limited environ-
ment), which is analogous to maturity— which often do follow
each other in this order— he explains their relationship thus:
334 EARTH'S SHIFTING CRUST
The sequence radiation-intrazonal evolution is usual, simply be-
cause radiation does not occur unless there are diverse zones within
which evolution will follow. Occasionally, nevertheless, something
happens to close the zones so soon that radiation is curtailed, or the
intrazonal phase is even shorter than the radiation. The camariate
crinoids, for instance, seem to have been in the full swing of a radia-
tion when they all became extinct in the Carboniferous. . . . (390:
232).
We note that Dr. Simpson says, "something happens." What
happens? He does not care to suggest what might happen to
close the zones, to curtail the radiation, to destroy the species.
No one has ever suggested a reasonable explanation of these
things, but they can be understood as effects of repeated dis-
placements of the crust.
Dr. Simpson has remarked elsewhere that he does not ob-
ject to the analogy of the species and the individual, provided
it may be allowed that youth may follow maturity, and may
occur more than once!
Not only may phases occur in the wrong order, and be
repeated, but also some may be omitted altogether. This
seems particularly true of the last, or so-called senile, period.
No concept has had so wide a currency with so little support
in evidence as that of the alleged degeneration of species.
The reasoning behind it is essentially specious: if a form of
life becomes extinct, and if some "exaggerated" trait can be
pointed to, which might have produced this extinction, then
it is claimed that the species was degenerate. This is, of
course, merely hindsight, because it ignores the fact that
some of the oddest creatures in the world have lasted for
millions of years and still exist. It is true that some kinds of
plants and animals become adapted to very narrowly special-
ized environments, so that an almost imperceptible change
in the environment may destroy them. These forms may, if
you like, be called overspecialized, but they cannot be called
degenerate. No inner process of decay has taken place in the
organism. Its extinction results from the external circum-
stance that destroys its relationship with its environment. Is
the specialist, who has spent his entire life in the study of
LIFE 335
the pre-Cambrian, and therefore is incapable of making his
living in any field outside of geology, or even outside pre-
Cambrian geology, degenerate? If he starves to death, is his
extinction due to degeneration? The reasoning is analogous.
But, supposing that we allow a phenomenon of degenera-
tion in species, it is still true that most species disappear with-
out showing any indication whatever of a decline of their
'Vital force/' The majority of them are cut off in the vigor
of maturity, or in "youth," as in the case of the camariate
crinoids. Moreover, there is no rule as to the relative length
of the different periods. Dr. Simpson remarks:
Diversification may be brief or prolonged, and may be of limited
scope or may ramify into the most extraordinarily varied zones cover-
ing a breadth of total adaptation that would have been totally unpre-
dictable and incredible if we were aware only of the beginning of
the process (390:222-23).
Again, he says,
. . . Episodes of proliferation may come early, middle or late in
the history of a group. This confirms the conclusion that adaptive
radiation is episodic but not cyclic (390:235).
We have already noted that Darwin recognized that the
ordinary competition of species could not account for the
mass extinction of whole groups, of which, even then, there
were many known instances in the fossil record. Since his
day, paleontologists have found very many more cases of
apparently well-adapted species, which in some cases had
flourished for tens of millions of years and yet suddenly dis-
appeared, sometimes leaving their life niches empty, and at
other times giving way to inferior species as their successors.
For the Pleistocene alone, the last million years, as we have
seen, the examples of this include the mammoth, the masto-
don, the sabertooth cat, the giant beaver, the giant sloth, the
giant bison, and countless extinct varieties of still existing
forms like horses, deer, camels, peccaries, armadillos, wolves,
bears, etc. Dr. Simpson, in discussing the extinction of the
dinosaurs, remarks:
336 EARTH'S SHIFTING CRUST
It should be emphasized that these mass extinctions are not in-
stantaneous, or even brief, events. They extend over periods of tens
of millions of years. . . . This makes the phenomenon all the more
mysterious, because we have to think of environmental changes that
not only affected a great many different groups in different environ-
ments, but also did so very slowly and very persistently. The only
general and true statement that can now be made about, say, the ex-
tinction of the dinosaurs is that they all lost adaptation in the course
of some long environmental change the nature of which is entirely
unknown (390:302).
If the dinosaurs lost adaptation, it was not because they
changed. The same is true of the sabertooth cat, which had a
life span of 40,000,000 years and, according to Simpson, was
apparently as well adapted at the end of that period as at
the beginning (392:43-44). The gradual elimination of the
dinosaurs can be understood as the result of constant shift-
ings of the earth's crust, which eliminated these reptiles first
in one area and then in another. No doubt, dinosaurs re-
peatedly reoccupied areas from which they had previously
been eliminated, but eventually— perhaps much more re-
cently than some people think— they were destroyed. Being
cold-blooded creatures, of course, they would find it quite
intolerable to be shifted into the cold zones, but there is not
the slightest reason to think they were degenerate. Simpson
attacks the entire idea of degeneration of species (392:72, 81).
He quotes Rensch:
In innumerable cases lineages become extinct without there being
recognizable in the last forms any sort of morphological or patholog-
ical degenerative phenomena (390:292).
Professor Dodson gives a good example of the piecemeal
extinction of species. He cites the case of the mastodonts,
relatives of the elephants, which became extinct first in the
old world and then in the new (115:371). Other examples
could be cited from the Pleistocene, when many species be-
came extinct in the Americas, while their close relatives, such
as horses, camels, and various kinds of elephants, survived
in the Eastern Hemisphere. Now one might ask the question,
LIFE 337
If a species becomes extinct on one continent but continues
to flourish on another, is it or is it not senile? What stage is
it in then? We can understand all these events as the results
of piecemeal destructions of animal populations in crust
displacements. We can see in them the process of the creation
of empty environments, preparing the way for a new stage
of explosive evolution. Simpson directly suggests the connec-
tion between these two things:
. . . Opportunity may come as an inheritance from the dead, the
extinct, who bequeath adaptive zones free from competitors. Jurassic
Virenz for ammonites followed extinction of all but one family, per-
haps all but one genus, of Triassic ammonites; early Tertiary mam-
malian Virenz followed mysterious decimation of the Cretaceous
reptiles. . . . (392:73)-
There is another question regarding the extinction of
species that should be answered. Perhaps it will be asked, If
crust displacements killed off the dinosaurs, why did they
not eliminate also the very numerous other reptiles that still
survive? If the last displacement at the close of the Pleisto-
cene eliminated the mammoth and certain other mammals
from America, why did other animals survive? The answer
is, essentially, that it is a question of the mathematical
chances of survival. It is a question of the numbers of the
animals, the geographical extent and variety of their habitats,
their particular individual aptitudes, and the ever-present
factor of sheer accident. It may be true that size militated
against some species, but it may have worked in favor of
others. The very largest animal of all— the whale— still sur-
vives. Elephants compare favorably with all but the very
largest extinct mammals.
7. The Gaps in the Fossil Record
One further point remains for our consideration. A feature
of the fossil record that greatly impressed Darwin was the
curious way in which species appear, full-blown, with no
338 EARTH'S SHIFTING CRUST
indication of transition forms, much like the mythical birth
of Venus. The paleontologist suddenly comes upon a species,
or a whole group of them, which have not been found be-
fore. They are all fully evolved; they obviously have had
long histories; there must have been hundreds or even thou-
sands of ancestral forms for them; but absolutely no trace of
the preceding forms can be found. It happened this way with
the dinosaurs, which appeared in Africa, with a great many
species already fully developed, at the beginning of the
Mesozoic Era. They seem to have come, literally, out of noth-
ing. Sometimes ancestral forms of a particular plant or ani-
mal will be found at a great distance—on another continent,
perhaps— but always there appear to have existed many inter-
mediary links, which have been lost. Even in the case of the
horse, where an unusually good record exists, there are many
missing links.
A part of the reason for this situation is, of course, the
imperfect preservation of the fossil record. There appear to
be several reasons for this. Fossilization itself is a very rare
event; very few individuals of any species are preserved, and
the great majority of all the species that have existed have
disappeared without a trace. Then, of the fossils that were
preserved in the rocks since the beginning of the sedimentary
record, about 95 per cent have been destroyed, since about
that percentage of all the sedimentary rocks of the older
periods has been eroded away and redeposited, with conse-
quent destruction of all fossils. Finally, of the fossils that
have been preserved, it is very unlikely that paleontologists
can have seen and studied more than a very insignificant pro-
portion—let us say, to put the matter as liberally as possible,
that they may have seen one millionth of the existing fossils.
Many of the latter, of course, are buried deep in the earth
or under the numerous shallow seas, and will never be seen.
But true as this is, it does not quite satisfy. Relatively few
and scattered as fossils may be, it is still to be wondered at
that we do not have a respectable handful of reasonably com-
plete life histories. The light cast on this matter by the theory
LIFE 339
of crust displacement is quite startling. We have seen that
such movements would necessitate frequent migrations of
whole faunas and floras. It would necessarily follow, from the
theory of crust displacement, that species would as a rule be
separated by considerable geographical distances from the
places of their origin. This would be all the more certain
since the rate of development of new forms is probably very
slow as compared with the rate at which crust displacements
may occur. It could, actually, be rather seldom that one plant
or animal would complete much of its life history in the same
place. The "missing links" would usually have been sepa-
rated by great geographical distances from the homes of their
descendants. Moreover, the successive movements of the
crust, with the resulting changes in the distribution of land
and sea, would leave much of the fossil record under the pres-
ent shallow (or even deep) seas, and out of our reach.
8. Summary
To sum up: it would seem that in crust displacements we
have the missing factor that can bring all the other evolu-
tionary factors into proper focus and correct perspective. By
crust displacements we may accelerate the tempo of natural
selection, provide the conditions of isolation and competition
required for change in life forms, and account for periods of
revolutionary change, for the distribution of species across
oceans and climatic zones, and for the extinction of species.
We may also account for the significant association of turn-
ing points in evolution with geological and climatic changes,
presenting them as different results of the same cause. But for
crust displacements to have had these effects, and if they are,
indeed, to account for the evolution of species, they must
have occurred very often throughout the history of the earth.
XI : CAMPBELL'S MECHANISM OF
DISPLACEMENT
i. The Logic of the Evidence
Readers of this volume may have reached the conclusion
that displacements of the earth's crust have occurred, perhaps
frequently, and very recently in the earth's history, and yet
they may doubt that the icecaps caused the displacements.
It may seem to them that other causes may have brought
about these effects, or perhaps that a combination of causes
has done so.
There are several reasons for concluding that the cen-
trifugal effects of asymmetrically placed icecaps were, in fact,
the cause of the displacements. The first of these is that con-
tinental icecaps are the most massive and the most rapidly
developed dislocations of mass known to have occurred at
any time on the earth's surface. All other known geological
processes subject to measurement, such as erosion and vol-
canic activity, are inadequate in tempo or in quantity to
produce equal centrifugal effects. No dislocation of mass
within the earth, known or conjectured, can compare quanti-
tatively in equal periods of time with the effect of an icecap
of the magnitude of the present icecap in Antarctica. Every
theory so far advanced to account for changes at the surface
of the earth (such as displacements of the crust) by changes
in depth have postulated long periods for the completion of
the changes. The geological evidence presented in this book
can be understood only in terms of displacements of the crust
at very short intervals during at least a large part of the
earth's history, with a most recent displacement through no
less than 2,000 miles of latitude in a period of about 10,000
years at the end of the North American ice age.
All this evidence calls for a large displacing force that
CAMPBELL'S MECHANISM 341
will overcome the inertia of the crust and its friction with
the layer below it, to continue the displacements to distances
of the order of several thousand miles. It is essential to have
a force that will not be absorbed and exhausted by the work
of moving the crust. It is clear that the mechanism of cen-
trifugal effect postulated by Campbell can meet this re-
quirement because the effect increases in proportion as the
uncompensated mass of the icecap is moved farther from the
axis of rotation. At the same time, as I have already men-
tioned, a cause of displacement is called for that will cease to
exert these centrifugal effects at some distance from the pole,
but long before the equator is reached. To accomplish this,
the mechanism must provide that the mass responsible for
the displacement must itself disappear en route, and, as we
have seen, it must disappear rapidly. It seems that the melt-
ing of the icecap, as the movement brings it into warmer
latitudes, provides not only a sufficient but perhaps the only
conceivable method of explaining the facts.
Campbell has made this clear by computing the increase
of the centrifugal effect with increasing distance from the axis
for the present Antarctic icecap, assuming it to be uncom-
pensated, and assuming its displacement, without melting,
as far as the equator. He has shown (Table III, opposite p.
341, and Figure XII, p. 343) that if the icecap should be dis-
placed as far as the 45th parallel of South Latitude, the
tangential component of its centrifugal effect would be mul-
tiplied about six times. After this point, while the total
centrifugal effect operating at right angles to the axis con-
tinues to increase until the equator is reached, the tangential
component declines, and yet it is clear that the movement,
if the uncompensated mass itself remains intact, must con-
tinue to the vicinity of the equator itself. The geological
evidence already presented shows that this did not occur, but
that the movements terminated at points about one third of
the distance from the pole to the equator.
In view of the apparently inescapable logic of the geo-
logical evidence and of the centrifugal mechanics, we must
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CAMPBELL'S MECHANISM
343
examine with some care the mechanism that Campbell pro-
poses as an explanation of displacements.
2. Calculating the Centrifugal Effect
I have already mentioned how preliminary calculations were
made of the possible centrifugal effect of the Antarctic cap.
I have mentioned that the calculation was first made by
Buker, and later somewhat revised by Campbell. However,
Campbell recognized, early in his examination of the theory,
that this effect, since it operated at right angles to the axis
of rotation and was not tangential to the surface, would not
produce a horizontal movement of the crust, even if the
magnitude of the effect was sufficient for the purpose. It
would be necessary, he felt, to find the tangential component
of the total quantity of the centrifugal effect. He ac-
complished this by the application of the principle of the
parallelogram of forces (Figure XII). However, his use of the
METRIC TOWS
Fig. XII. The Centrifugal Effect of the Icecap. Use of the Parallelo-
gram of Forces to Calculate the Tangential Component
344 EARTH'S SHIFTING CRUST
principle is not that usually presented in high school and
college textbooks of physics. The definition of the law of the
parallelogram of forces is as follows:
If two forces acting on a point be represented in direction and
intensity by the adjacent sides of a parallelogram, their resultant will
be represented by that diagonal of the parallelogram which passes
through the point (249:489).
In the three parallelograms in Figure XII, the two forces
acting on the point a are the force of gravity, represented by
the line a-d (a radial line to the center of the earth), and the
tangential component of the centrifugal effect of the icecap,
represented by the line a-c, while the "resultant" of these
forces is the diagonal a-b, at right angles to the axis of rota-
tion. The reader will note that Campbell has here inverted
the terms of the definition but without changing the quanti-
ties of the forces in relationship to each other. The "re-
sultant* ' in the definition is our starting point; it is the
estimated total centrifugal effect of the icecap. But it is evi-
dent that it is unimportant whether the given quantity is the
diagonal or the side of the parallelogram; the parallelogram
permits the finding of the unknown quantity from the known
quantity, whichever the latter is. The parallelogram there-
fore permits a finding of the quantity of the tangential com-
ponent. The rotating effect of this force exerted on the
earth's crust is illustrated by the weight shown in Figure XIV.
By definition, the tangential component of the centrifugal
effect is exerted horizontally on the earth's crust. Now the
question arises as to whether this force will be exerted on
the crust itself, or whether it will act on the earth's body as
a whole, and thus tend to be dissipated in depth. This is the
same as the question whether the icecap will tend to shift the
whole planet on its axis or merely to shift the crust. We have
already decided that it will tend to shift the crust only, be-
cause of the existence of a soft, viscous, and plastic layer
under the crust. We may therefore conceive of this force,
the tangential component of the total effect, as acting on the
CAMPBELL'S MECHANISM 345
crust alone, while recognizing that the displacement of the
crust involves frictional effects with the sublayer. We have
seen that a special characteristic of the mechanism under
discussion is that it provides a constantly growing force that
will overcome this friction, rather than be absorbed by it.
3. The Wedge Effect
The problem to be solved by the calculation was to find the
quantity of the centrifugal thrust of the icecap in terms of
pressure per square inch on the earth's crust, so that this
quantity could be compared with the estimated tensile
strength of the crust. If these quantities should be found to
be of about the same magnitude, it would follow that the
icecap had the potentiality of bringing about the fracturing
of the crust, which, because of the slightly oblate shape of the
earth, was necessary to its displacement over the lower layers.
Einstein, in a letter received during an early stage of the in-
vestigation, suggested that this necessity for the fracturing
of the crust was the only serious hindrance to crust displace-
ments in response to centrifugal effects. He wrote:
For your theory it is only essential that an excentrically situated
mass rising above the mean level of the earth-surface is producing a
centrifugal momentum acting on the rigid crust of the earth. The
earth-crust would change its position through even a very small cen-
trifugal force if the crust would be of spheric symmetry. The only
force that I can see which can prevent such sliding motion of the
crust is the ellipsoidic form of the crust (and of the fluid core). This
form gives to the crust a certain amount of stability which allows the
dislocation of the crust only if the centrifugal momentum has a cer-
tain magnitude. The dislocation may then occur and be accompanied
by a break of the crust. . . . (128).
Campbell, visualizing the sliding of the crust, perceived that
a bursting stress would be caused in the crust when parts of
it were displaced toward or across the equatorial region,
where the diameter of the earth is greater. It became possible
to visualize it in the manner suggested by Campbell in the
346
EARTH'S SHIFTING CRUST
lower left-hand drawing of Figure XIV. The drawing shows,
in black, two wedge-shaped cross sections representing the
earth's equatorial bulge, or that part of it underlying the
areas of the crust moving equatorward in the displacement.
Half of the bulge is, in fact, involved; the other half under-
lies the areas of the crust being simultaneously displaced
poleward, but these do not affect the point at issue.
The reader will note that the equatorial bulge of the earth
is represented in this drawing as lying underneath the crust,
so that the crust is not a part of it. This is a new way of visu-
alizing the bulge, introduced by Campbell, and justified by
him on the ground that since the earth's crust is of the same
general thickness all over the earth regardless of latitude
(even though it may be of differing thicknesses from place to
POLAR AX 1 5
Fig. XIII. A Cross Section of the Earth Showing the Relation Between
the Crust and the Equatorial Bulge
CAMPBELL S MECHANISM
347
NORTH POLE
CROSS SECTION OF EARTH ON
96* EAST
Fig. XIV. Various Aspects of the Wedge Effect
The Antarctic continent is shown, with center of gravity displaced to
the right, on a line representing the $6th degree of East Longitude. The
figure at the right represents the continuation of the movement of the
icecap along this meridian, mounting the bulge, which must be visualized
three-dimensionally. The lower left-hand figure shows the vertical cross
section of the earth under the icecap, with the two wedges pushing the
crust out as it approaches the equator. The proportions of the wedges
ate shown, and an equilibrium of equal and opposite pressures is indi-
cated. The tangential pull of the icecap is indicated by the suspended
weight.
place, and under mountains, continents, and ocean basins),
then the differences in the polar and equatorial diameters of
EARTH'S SHIFTING CRUST
CONVENTIONAL
TYPE OF WEDGE:
P« PRESSURE OF ICECAP « 7.5 » I o'* SHORT TON8
b - DEPTH OF WEDGE « 6.0 MILK*
Q « pwesauRt AGAINST '
LITHOSPHCRE
• A.73»IO 4MORT TONS
CROSS SECTION OF EARTH AT
96™
Fig. XV. The Wedge Effect
the earth are accounted for by differences in the thicknesses
of the layers underlying the crust, and the bulge itself repre-
sents added matter in the subcrustal layers in the equatorial
regions.
The bulge, viewed in this way as lying beneath the crust
appeared to form two wedges against which the crust had
to be displaced by the centrifugal thrust of the icecap. Camp
bell reached the conclusion that to estimate the bursting
stress produced on the crust in the equatorial region, il
would be necessary to apply the mechanical principle of the
CAMPBELL'S MECHANISM 349
wedge, which has the effect of multiplying the effect of an
applied force. This principle is usually given as follows:
The wedge is a pair of inclined planes united by their bases. In the
application of pressure to the head or butt end of the wedge, to
cause it to penetrate a resisting body, the applied force is to the
resistance as the thickness of the wedge is to its length (249:512).
This statement means that a wedge multiplies the splitting
power (or bursting stress) produced by an applied force in
the proportion of the length of the wedge to its thickness at
the butt end. Figure XV shows the application of this prin-
ciple to the earth. The formula for calculating the wedge
effect is presented at the extreme left, where P = pressure (as
thrust of the icecap transmitted to the crust), Q = the mutual
pressure between crust and bulge, or bursting stress, h = the
height (that is, the length) of the wedge, and b = the base or
butt end. The bursting stress equals the pressure applied to
the butt and multiplied by the ratio of the thickness of the
butt end to the length of the wedge. The length of the wedge,
in this case, is about 6,000 miles, and its thickness at the butt
end is 6.67 miles, so that the ratio is about 1,000:1, and the
quantity of the thrust of the icecap should consequently be
multiplied by 1,000; however, there are two wedges, one on
each side of the earth, and therefore the thrust is multiplied
only 500 times. Nevertheless, the significance of such a multi-
plication of the effect of the icecap is self-evident.
It was not a simple matter to apply the principle of the
wedge to the earth. As in the case of the principle of the
parallelogram, the formula could not simply be copied from
a textbook; it had to be imaginatively applied. For example,
in the diagram P, or pressure, is shown exerted on the butt
end, like a sledge hammer hitting the butt end of a wedge to
split a log. But obviously, the thrust of the icecap is not, in
the first instance, applied in this way. It takes an act of the
imagination to realize that in effect it amounts to the same
thing. The icecap is really pushing or pulling the crust
toward the equator on both sides of the earth, but the matter
350 EARTH'S SHIFTING CRUST
may just as well be looked at in the opposite way, as if the
icecap and crust stood still, or were under no horizontal
pressure, but force was being applied to the butt end of the
wedge. Either way, the mathematics is the same. Campbell's
application of this principle to the problem of estimating the
bursting stress on the crust was discussed with physicists, in-
cluding Frankland, Bridgman, and Einstein (see below), none
of whom questioned its soundness.
After finding the quantity of the total stress on the earth's
crust produced by the centrifugal effect transmitted from
the icecap, Campbell reduced it to pressure per square inch
by dividing it into the number of square inches in a cross
section of the earth's crust, assuming an average thickness of
the crust of about 40 miles. This estimate of the crust's thick-
ness is a liberal one, since some writers, including Umbgrove,
suggest that it may be no more than half as much. Since a
lesser thickness for the crust would mean a higher figure for
the bursting stress per square inch, an error in this direction
here may serve to counter the effect of the possible partial
isostatic compensation of the icecap, which we have disre-
garded in the tentative calculation of its centrifugal effect.
Thus, if half the icecap is isostatically compensated, but the
crust is only 20 miles thick, then Campbell's estimate of the
pressure per square inch will be unchanged.
Campbell found that the bursting stress on the crust per
square inch amounted to about 1,700 pounds (see p. 361). In
comparison with this, I found that the crushing point of
basalt at the earth's surface has been estimated, from labora-
tory experiments, at 2,500 pounds. A number of points must
be considered in reaching conclusions regarding the possible
significance of these comparative figures. First, the crushing
strength of any rock is considered to be higher than its
tensile, or breaking strength. Thus, the tensile strength of
basalt, the principal constituent of the earth's crust, is proba-
bly considerably closer to the estimated quantity of the
bursting stress. A second important consideration is that
the earth's crust is unequal in thickness and strength from
CAMPBELLS MECHANISM 351
place to place, and is everywhere penetrated by deep frac-
tures. It would naturally fail at its weakest point. As we shall
see below, Einstein, in view of these facts, said that he would
be satisfied as to the plausibility of the mechanics of this
theory if the ratio of the bursting stress to the strength of the
crust was 1:100. The ratio as shown by Campbell is very
much closer than the ratio demanded by Einstein. It seems
therefore reasonable to suppose that at some point of the
future growth of the icecap, which is now, it appears, still
growing, the crust may respond to the increasing bursting
stress by fracturing. When this occurs, it may be expected
that a process will begin of gradual fracturing and folding of
the crust, accompanied by the beginning of its displacement
over the underlying layers.
Campbell has pointed out that no very great force is re-
quired to accomplish a widespread fracturing of the crust
during a displacement. At the first local failure of the crust
in response to the bursting stress, the stress will be relieved
at that point, to become effective immediately at an adjacent
point. Thus the fracture will travel through the crust with-
out the application of additional force. From this it is clear
that the steady application of a small force would suffice to
fracture the crust to a great distance. In his conversation with
Einstein, an account of which is given below, Campbell gave
a convincing illustration of this principle.
The ability of the crust to resist fracture is slight. Jeffreys
found that a strain equal to the weight of a layer of rock 2,200
feet in height would fracture it to its full depth (238:202).
It is clear that the tensile strength of the crust does not com-
pare with its crushing strength, which, also according to
Jeffreys, is sufficient to enable it to transmit mountain-mak-
ing stresses to any distance. Campbell visualizes the proc-
ess of crust displacement not as a continuous movement but
as a staged movement resulting from an interaction alter-
nately of the direct thrust of the icecap and of the bursting
stress. He writes:
352 EARTH'S SHIFTING CRUST
. . . There are two distinctly separate functions performed by the
mass of the icecap. . . . The first is the centrifugal momentum caus-
ing the lithosphere to change its position in relation to the poles. . . .
When the lithosphere comes to a standstill for want of a sufficient
force, the second function of the icecap gets busy and builds up a
pressure of tremendous potential, five hundred times the force pro-
duced by the icecap, and will continue to add to this pressure at the
rate of five hundred times the increasing pressure of the growing
icecap, until it finally splits the lithosphere. Then the pressure will
drop, and the first function will take hold, and once again start to
move the lithosphere. This alternate action will continue to take
place until the icecap is destroyed. . . .
. . . The wedge does, not multiply the power of the centrifugal
momentum, as such. The power disposed for the movement of the
lithosphere remains the same as it always has been, but the static
pressure that will fracture the lithosphere, thereby permitting the
centrifugal momentum of the icecap to start moving the lithosphere,
will be multiplied by 500.
The wedge has been functioning ever since the first permanent
snow fell on the Antarctic continent; it is functioning today. ... At
the same time, die centrifugal momentum of the icecap is just stand-
ing by, waiting for the lithosphere to fracture and be released for the
journey toward the equator. The tensile strain will fade away with
the faulting of the lithosphere, but should the fractures freeze up
again from any cause, the tensile strain will tend to build up again,
and the same series of actions will repeat themselves (66).
We saw that the process that destroyed the Wisconsin ice*
cap was several times interrupted and renewed in alternating
withdrawals and readvances of the ice, which we have ex-
plained as resulting from episodes of massive volcanism.
These phases appear to correspond to the alternating phases
of the process of displacement as suggested by Campbell,
which would naturally have been accompanied by volcanic
activity.
4. Some Difficulties
A number of objections have been raised, in the course of
consultations with specialists, to the mechanism of displace-
CAMPBELL'S MECHANISM 353
ment suggested by Campbell. We have considered these ob-
jections, and they do not appear formidable. I am summariz-
ing some of these in the following pages, in order that the
reader may know, if any of these have occurred to him, that
they have already been given consideration.
a. The question of friction with the subcrustal layer. It
may at first appear that friction would be a powerful brake
on any extensive displacement of the crust, and unquestion-
ably it would have an effect. Yet there are several mechanical
factors that could aid a displacement. A leading considera-
tion is that the suggested movement is a gliding motion.
Gliding is the most economical form of motion. It has been
said, in fact, that gliding constitutes an ideal form of motion
that utilizes 100 per cent of energy, as opposed to the sphere
and the cylinder, which, being round, lose 30 per cent of
their energy in rotation, which reduces their speed consider-
ably. Frankland has suggested that a rise of temperature at
the interface of the crust and the lower layer, as the result
of friction, could facilitate a displacement. Campbell con-
siders that the underlayer, or asthenosphere, would act more
like a lubricant than a retardant. He compares the movement
to the motion of ice floes: ". . . Observe how vast fields of
ice are started in motion just by the friction of the wind on
the surface of the ice. . . . Again, you will see the same
thing by visiting a pond where they are cutting ice. You will
see men pushing around blocks of ice of three or four hun-
dred square feet with the greatest ease as long as the ice is
floating in the water. . . ."
b. The question of the extent of the displacement. It has
been questioned whether a displacement of the crust might
not terminate at an early stage because of the melting of
the icecap as it moves into lower latitudes. Campbell, how-
ever, has pointed out that as the icecap moves equatorward
from a polar region, the ice will continue to accumulate on
the rear or poleward side, and that this will have the effect
of prolonging the motion of the crust. In some circumstances,
if the icecap happened to be situated on a very large land
354 EARTH'S SHIFTING CRUST
mass, this might mean a long continuation of the movement.
An icecap in Eurasia might move the crust a great distance.
It is obvious that a natural point for the termination of the
movement will be the arrival of an oceanic area at the pole,
so that the rearward build-up of the ice is brought to an end.
This would appear to have happened in the last movement,
when the southward shift of North America seems to have
brought the Arctic Ocean into the polar zone.
c. The question of the possible suspension of movements
if both poles should happen to be situated in oceans. This is
one of the more important objections that have been raised
to Campbell's mechanism of displacement. Yet, it appears
that it is much less formidable a difficulty than it seemed at
first glance. It might be supposed that the eventuality of
having both poles in water areas would be certain to occur;
that is, it would have occurred early in the earth's history,
and would have stopped crust displacements by putting an
end to the formation of great polar icecaps. However, a
further examination of this objection reveals weaknesses in it.
In the first place, the very peculiar placing of the conti-
nents with respect to the ocean basins renders such an event
almost impossible. All the six continents are placed dia-
metrically opposite oceans on the other side of the globe.
Ninety-five per cent of all the land on the globe lies opposite
water. Moreover, the oceans are surrounded by continental
shelves that extend for considerable distances, and there are
island areas in the oceans where the water is comparatively
shallow. We have seen that, according to Gutenberg, any
part of the earth's surface moved poleward by a crust dis-
placement would stand higher relatively to sea level. Any
area now near the equator would be raised considerably if
moved to a pole, by reason of the variation of gravity alone,
while other factors might add to the vertical movement
(Chapters IV, V, VI). Displacements could result in raising
the continental shelves, shallow seas, and island areas above
sea level. The two or three displacements of the crust in the
same direction that would be required to move any area from
CAMPBELL'S MECHANISM 355
near the equator to the vicinity of a pole might produce
major increases in elevation. Finally, it would be necessary for
both poles to be so far away from the nearest land as to pre-
vent the growth of icecaps on any side, for an icecap formed
all on one side of a pole and at a considerable distance from
it would have a very great centrifugal effect proportionately
to its size. Campbell carried out a series of careful measure-
ments of the globe to find out how many possibilities actually
exist at the present time for the location of both poles in
water. He found that there is only one such position, where
one pole would be in the South Atlantic and the other in the
North Pacific between the Marshalls and the Carolines. But
the latter area, in the course of its displacement from its pres-
ent latitude to the vicinity of a pole, could easily be raised
above sea level.
It cannot be denied, despite this, that there exists a real
possibility that at various times during the history of the
globe both poles have been, in fact, situated in oceanic areas.
Unquestionably, this would have resulted in the temporary
cessation of the formation of great polar icecaps, and there-
fore of displacements of the crust. However, there is no rea-
son to conclude that this would have meant a permanent
cessation of crust displacements. We must not forget that
Gold has suggested a mechanism by which a shift of 90 de-
grees in the positions of the poles could occur in periods of a
million years. In this way a period without crust displace-
ment could be ended by the gradual movement of a new land
area to a pole. It is even quite possible that the accumulation
of inequalities of mass within the crust itself, as the result of
erosion or of igneous processes, might eventually produce a
displacement without the agency of an icecap.
d. The question as to why the postulated centrifugal effect
has not prevented the accumulation of the icecap. One com-
mentator has pointed to the well-known fact that ice flows
outward in all directions from a central point or points,
through the effects of its own weight, and has argued that the
centrifugal effect should operate to make the icecap flow off
356 EARTH'S SHIFTING CRUST
into the sea rather than to bring about a transfer of centrif-
ugal momentum from the icecap to the crust. This objection
has a certain plausibility at first glance, and yet it is invalid
for the following reason. We know that according to classical
mechanics any mass deposited upon the earth's surface (pro-
vided that surface is already in gravitational equilibrium) will
be acted upon by the earth's rotation, and will give rise to a
centrifugal effect. So much cannot be denied. It is also true
that the resulting centrifugal momentum will act upon the
ice and can be expected to accelerate to some degree the
rate of flow of the ice in the direction of the thrust (not in
all directions). In the case of the present Antarctic icecap
this might mean a slightly increased rate of flow across the
broadest section of the continent, in the direction of the
meridian of 96° E. Long, (see the map of Antarctica, Intro-
duction, p. 18). However, the crux of the matter is, obviously,
the ratio of the rate of flow to the rate of accumulation of the
ice. It is clear, on the one hand, that new ice, until brought
within the equilibrium surface of the globe by isostatic ad-
justment, must give rise to centrifugal effects; and on the
other hand it is quite clear that, despite this, the icecap has
continued to accumulate. Why does it happen that the cen-
trifugal effect does not produce a flow-off of ice from the
continent at a rate equal to the rate of accumulation? The
answer to this is, obviously, that ice presents considerable
resistance to flow. It flows only under considerable pressure,
and is otherwise a solid. Moreover, in Antarctica, and pre-
sumably in any polar icecap, the prevailing low temperatures
cause the ice to have increased rigidity. It is also thought that
the ice below the superficial layers of a great ice sheet is stag-
nant, and that only the upper layers move. This means that
the ice that is in contact with the ground is fixed to the
earth's surface. The viscosity, or stiffness, of the ice in turn
means that a drag is imparted by the upper layers to the
lower layers, and by them to the underlying crust. Thus the
centrifugal momentum is transmitted to the crust. Finally,
the supposition of the gliding off of the icecap is rendered
CAMPBELL'S MECHANISM 357
more improbable by the uneven topography of the continent
and especially by the great fringing mountain ranges. We
have cited Einstein's opinion that the flow-off of ice from
Antarctica in the form of icebergs is an insignificant percent-
age of the annual ice accumulation.
e. The question as to whether the centrifugal effect postu-
lated in this theory exists at all. Some commentators have
rejected the idea that a large total centrifugal effect may be
created by the asymmetric accumulation of an icecap. They
have agreed only to the existence of a centrifugal effect that
may be created if the center of mass of an object is elevated
above the equilibrium surface of the earth. This has been
termed the Eotvos effect. It does not depend upon the exist-
ence of excess mass at a point. It may be illustrated by an
iceberg floating in water. The ice is in gravitational balance,
having displaced its weight of water. But one tenth of its
weight is above the surface of the water. The center of its
mass is therefore higher than the center of the displaced
water. If the center of its mass is further from the earth's
center, it is now moving around the earth's center at a faster
rate. It has been accelerated, and the tangential component
of the acceleration will tend to move it toward the equator.
This concept is well known in geophysics, and conse-
quently it has been the customary mode of considering any
question involving centrifugal effects on the earth's surface.
But the effects that may arise from an accumulation of ice
that has not been brought within the equilibrium surface of
the earth by isostatic adjustment, and which therefore con-
stitutes an accumulation of excess mass at a point on the
surface, have not received equal attention. I have already
mentioned the fact that the idea came to both Bridgman and
Daly as a new idea, and one that seemed to them worth in-
vestigating. Because of the special importance of this issue,
I am presenting a more detailed discussion of it below.
f. The question as to whether the crust is strong enough
to transmit the centrifugal momentum of the icecap. A num-
358 EARTH'S SHIFTING CRUST
ber of consultants have been in doubt on this point because
of their knowledge that the crust is, from certain points of
view, very weak. It has little tensile strength, and as a conse-
quence cannot bear heavy loads without fracturing or giving
way by plastic flow. However, tensile strength and crushing
strength are two very different things. A bar made of a brittle
but hard substance will have little tensile strength, but con-
siderable force may be required to crush it. The rocks com-
posing the earth's crust are highly rigid, and therefore, de-
spite the fact that they have little tensile strength, such as
would be required to contain vertical stresses, they have
enormous strength to resist horizontally applied compressive
stresses. They simply cannot be compressed to any extent,
and only an enormous force will produce plastic flow. The
rocks of the crust are so rigid (despite the fact that they do,
of course, possess a certain small degree of elasticity) that the
penetration of the crust by fractures does not seriously mod-
ify its power to transmit horizontal or tangential stresses.
There is geological evidence in the mountain systems, in the
planetary fracture systems, in the great globe-encircling can-
yon system recently discovered by Ewing, that stresses have
been applied to the earth's crust as a whole, and various geol-
ogists, including Hobbs and Umbgrove, have made state-
ments to that effect.
A proper understanding of this question requires that the
magnitude of the stress and its mode of application should
be considered. An enormous pressure per square inch, espe-
cially if applied all at once, might cause local deformation of
the crust by bringing about rock flow, as it has been sug-
gested by Bridgman (p. 189), but the stresses that we suppose
to derive from the icecap are not of this order, nor do they
reach their maximum intensity until after a period of gradual
growth during which they could be transmitted to the crust
as a whole. The icecap produces a gentle pressure, slowly
growing and steadily applied over a considerable length of
time, incapable of radically deforming the crust adjacent to
CAMPBELL'S MECHANISM 359
itself, but capable of exerting a persistent push on the earth's
crust.
If it were possible to exhaust the centrifugal effect of the
icecap by the absorption of energy in a local deformation of
the crust, the matter might wear a different aspect. But we
are to remember that, if the yielding of the crust or its dis-
placement as a whole allows the displacement of the ice mass
farther from the axis of rotation, the centrifugal effect is
thereby multiplied. In these circumstances the centrifugal
momentum cannot be absorbed locally, but must be trans-
mitted to the entire crustal shell of the earth.
Jeffreys has remarked that the earth's crust can transmit
mountain-building stresses to any distance (238: 2 £
5. The Calculations
The following are the calculations of the centrifugal effect
of the present Antarctic icecap, and of the resulting bursting
stress on the crust, as worked out by Campbell. The phraseol-
ogy is in part that of Dr. John M. Frankland, of the Federal
Bureau of Standards, who was kind enough to review these
calculations.
a. Calculation of the Centrifugal Effect of the Rotation of
the Antarctic Icecap:
Assume isostatic adjustment o, center of gravity of the ice-
cap 345 miles from the polar axis, and volume of the ice
equal to 6,000,000 cubic miles.
W = Weight of the icecap = 2.500 X 1Ql6 short tons.
F = Centrifugal effect in pounds = — — , where
gR
v — Velocity of revolving icecap, 132 feet per second,
R = Distance from the axis of rotation to the center of
gravity of the icecap = 345 miles = 1,821,600 feet,
g = Acceleration due to gravity = 32.
360 EARTH'S SHIFTING CRUST
F _ Wv2 _ 2.5 X i°16 X
gR 32 X 1,821,600
43*870.75 X iQ16 _
58,291,200
7.5 X l°12 short tons = 6.8 X l°12 metric tons,
total centrifugal effect, 6.8 X l°12 metric tons,
radial force tangential to the earth's surface,
6.8 X 1C)2 metric tons (see p. 343).
This, of course, is an upper estimate, which may be too large
by a factor of two or three.
b. Calculation of the Bursting Stresses on the Lithosphere:
An approximation of the bursting stress caused by this cen-
trifugal effect can be reached by simple methods as follows.
More elaborate approaches hardly seem justified in view of the
uncertainty of the magnitude of the centrifugal force.
It is assumed that the entire resistance to the motion of
the lithosphere arises from the fact that the earth is not a
perfect sphere, but is an oblate spheroid. The tangential, or
shearing, stresses between the lithosphere and the underlying
asthenosphere are considered negligible because of the time
factor, and because of the assumed viscosity of the astheno-
sphere. If one considers the great circle passing through the
center of gravity of the icecap, at right angles to the meridian
of centrifugal thrust of the icecap, it is evident that the cir-
cumference of this great circle will be increased if the icecap
is displaced away from the pole. Of course, any stress system
that arises in this way will be two-dimensional, but one will
hardly be in error by a factor of more than two, if one neg-
lects the two-dimensional character of the stresses and as-
sumes instead that they are uniaxial. The only purpose of
this computation is, of course, to show the order of mag-
nitude of the effect.
With this kind of approximation, one may view the equa-
torial bulge as a kind of wedge up which the lithosphere is
CAMPBELL'S MECHANISM 361
being pushed. There are, of course, two wedges, one on each
side of the globe.
The bursting stress is the product of the tangential effect
of the icecap by the ratio of the gradient of the bulge:
(1) Thickness of bulge (wedge) at its butt end nn 6.67 miles.
(2) Ratio of travel to lift, of bulge wedge = 6, 152: 6.67
(3) Stress, on cross section of the lithosphere (taken as
40 miles thick) = 7.5 X 1Ql2 X 6,152
6.67 X 2
= 34588 X 1Ql5 short tons.
_ 34588 X io15 7
~ 5 = 3-5 X io7
99°>894
short tons per sq. mi.
— Approximately 1,700 Ibs. per sq. in.
6. Notes of a Conference with Einstein
In January, 1955, Mr. Campbell and I had the privilege of
a conference with Einstein at which a number of important
questions relating to the theory were discussed. Subsequently,
I prepared the following statement, which I submitted to
him for his approval. He approved it as an accurate report of
our discussion, but he desired that it should not be inter-
preted as an official endorsement on his part of Mr. Camp-
bell's calculations in detail, which he had had insufficient
opportunity to study. Those present at the meeting included
Dr. Einstein, Mr. Campbell, Mrs. Mary G. Grand, and myself.
After the introductory remarks, Mr. Hapgood explained
to Dr. Einstein that while, in the development of the theory,
he had himself been concerned mainly with the field evi-
dence in geology and paleontology, Mr. Campbell had con-
tributed the basic concepts in mechanics and geophysics.
Mr. Hapgood explained further that Mr. Campbell's cal-
culations had now advanced to a point where he felt that a
consultation was necessary. The principal question was
362 EARTH'S SHIFTING CRUST
whether the tangential portion of the centrifugal effect re-
sulting from the rotation of the icecap was of the correct
order of magnitude to cause fracturing of the earth's rigid
crust. Dr. Einstein had stated in a letter to Mr. Hapgood
that, owing to the oblate shape of the earth, the crust could
not be displaced without fracturing and that the tensile
strength of the crust, opposing such fracturing, was the only
force he could see that could prevent a displacement of the
crust. He had already suggested, therefore, that it would be
necessary to compare the bursting stresses proceeding from
the icecap with the available data on the strengths of the
crustal rocks.
It was this problem that now, through the calculations
made by Mr. Campbell, seemed to be solved.
Mr. Campbell explained to Dr. Einstein the principles he
had followed in making the calculations. He used photostatic
drawings as illustrations. He showed that the crust, in at-
tempting to pass over the equatorial bulge of the earth,
would be stretched to a slight degree. A bursting stress would
arise that would tend to tear the crust apart. This stress
would in all probability exceed the elastic limit of the crustal
rocks: that is, they would tend to yield by fracture, if the
stress was great enough. Dr. Einstein said, Yes, but he won-
dered how an equilibrium of force would be created? Mr.
Campbell pointed out that two equal and opposite pressures
would arise, since, at the same time, on two opposite sides
of the globe, two opposite sectors or quadrants of the crust
would be attempting to cross the bulge.
Dr. Einstein agreed that this was reasonable, but raised the
question of the behavior of the semiliquid underlayer of the
bulge, under pressure from the rigid crust. After some dis-
cussion it was agreed that this underlayer, despite its lack of
strength, would not be displaced, because of the effect of the
centrifugal momentum of the earth.
Mr. Campbell then explained the application of a prin-
ciple by which the tangential stress proceeding from the ice-
cap was greatly magnified. He considered that the bulge of
CAMPBELL'S MECHANISM 363
the earth, starting with zero thickness at the poles, and
proaching 6.67 miles in thickness at the equator, behaved
physically as a wedge resisting the movement of the crust.
Since the distance from pole to equator is about 6,000 miles,
the ratio of this wedge was 1,000:1; but the existence of two
wedges on opposite sides of the globe reduced the ratio to
500:1. The icecap's tangential effect, multiplied by 500, and
divided by the number of square inches of the cross section
of the lithospheric shell at the equator (assuming the crust
to be 40 miles thick), produced a bursting stress on that shell
of 1,738 pounds per square inch. After examining each step
in the argument twice Dr. Einstein had the impression that
the principles were right, and that the effects were of the
right order of magnitude. He stated that he would be satis-
fied if the bursting stress and the strength of the crust were
in the ratio of not more than 1:100, since the crust varied
so greatly in strength from place to place, and would un-
doubtedly yield at its weakest point.
Mr. Campbell explained an effect he had often observed,
which illustrated the process by which the crust might yield
to fracture. A common method of splitting a block of granite
is to drill two small holes, about six inches apart, near the
center of the long axis of the granite, and insert and drive
home a wedge in each hole, A bursting stress of sufficient
magnitude is brought to bear to split the rock. However, the
rock is not split all at once. Enough stress is brought to bear
to start a fracture, but the fracture does not take place in-
stantaneously. If the wedges are put in place in the evening,
it will be found next morning that the whole rock has been
split evenly along a line extending through the two holes.
The fracture has slowly migrated through the rock during
the night. The force required to split rock in this way is but
a fraction of that required to split it all at once. So far as the
earth's crust is concerned, what is required is not a force suf-
ficient to split it all at once, but simply a force sufficient to
initiate a fracture or fractures, which will then gradually
364 EARTH'S SHIFTING CRUST
extend themselves during possibly considerable periods of
time.
Mr. Hapgood next described the geological evidence of
world-wide fracture systems extending through the crust, and
weakening it, and the remarkable similarity of these patterns
to those which, theoretically, would result from a movement
of the crust. Dr. Einstein expressed the keenest interest in
this evidence.
Mr. Hapgood referred to the Hough-Urry findings of the
dates of climatic change in Antarctica during the Pleistocene.
Dr. Einstein stated that the method of radioactive dating de-
veloped by W. D. Urry was sound and reliable. As a re-
sult, Dr. Einstein was in full agreement that the data from
Antarctica, indicating that that continent enjoyed a tem-
perate climate at a time when a continental icecap lay over
much of North America, virtually compel the conclusion that
a shift of the earth's entire crust must have taken place.
Dr. Einstein asked Mr. Hapgood what objections geologists
had been making to the theory. Mr. Hapgood replied that
it was principally a question of the number of such move-
ments, Urry's evidence would imply four such displacements
at irregular intervals during the last 50,000 years.1 Dr. Ein-
stein replied that this seemed to be a large number. How-
ever, he said, if the evidence could not be explained in any
other way, even this large number would have to be accepted.
The gradualistic notions common in geology were, in his
opinion, merely a habit of mind, and were not necessarily
justified by the empirical data.
At this point the discussion turned to astronomy. Mr. Hap-
good did not understand why men who would boggle at the
rate of change required by the theory of crustal movements
thought nothing of accepting the view that the entire uni-
verse had been created in half an hour. Dr. Einstein said that,
unfortunately, the evidence seemed to point that way. After
iThis figure was subsequently revised, in the light of much geological evi-
dence (Chs. VII, VIII, IX), to three displacements in the last 130,000 years.
CAMPBELL'S MECHANISM 365
considerable discussion he added that it was not, however,
necessary to take the present state of our knowledge very
seriously. Future developments might show us how to reach
a different conclusion from the evidence. Much that we re-
gard as knowledge today may someday be regarded as error.
Toward the end of the interview Dr. Einstein indicated a
number of points where further research would be desirable.
He suggested the need for a gravitational study of the Antarc-
tic continent, and for a study of the rates of crustal adjust-
ment to increasing or decreasing loads of ice. He commented
upon the difficulties that confront those who wish to intro-
duce new theories, and quoted Planck's remark that theories
change not because anybody gets converted but because those
who hold the old theories eventually die off.
7. Isostasy and Centrifugal Effect
As I have mentioned, there is a possibility of two points of
view regarding the particular centrifugal effect postulated
by Campbell and myself. It is therefore necessary to provide
additional clarification of some of the points at issue. To a
certain extent it may be a question of a situation in which
new definitions or clearer definitions of accustomed terms
are called for, but it also appears to us that in some cases, at
least, physicists whom we have consulted in the course of our
work are proceeding upon the basis of assumptions that are
in conflict with ours. Therefore, it is necessary to re-examine
these assumptions. A comprehensive discussion of the matter
must begin with a review of the broader questions of the
mechanics of rotation already briefly referred to in the In-
troduction.
The existence of a very common misunderstanding re-
garding the mechanics of the earth's rotation, particularly
related to the problem of the stability of the poles, was made
clear to me by a difference of opinion that arose at the be-
ginning of my inquiry. Brown, whose work was the starting
366 EARTH'S SHIFTING CRUST
point of my own, was an engineer, and his concepts of the
earth's motions were based upon simple mechanics. He un-
derstood gyroscopic action, and the stabilizing role of the rim
of a rotating flywheel. He also understood the laws of cen-
trifugal effect as applied to weights eccentric to the axes of
spin of rotating bodies. It was my good fortune that Camp-
bell, who was to carry the work forward, also was a mechan-
ical engineer.
Brown had made the statement that it was the equatorial
bulge of the globe that stabilized it with reference to the axis
of rotation; he had compared it to the rim of a flywheel. I
found that this statement was disputed by some physicists.
The physicists suggested that the stability of the earth on
its axis was not owing to the centrifugal effect of the rota-
tion of the equatorial bulge alone, but to that of the rotation
of the entire mass of the earth. Later I discovered a passage
in Coleman that appeared to express their point of view:
It may be suggested that the earth is a gyroscope, and, as such, has
a very powerful tendency to keep its axis of rotation pointing con-
tinuously in the same direction. Any sudden change in the direction
would probably wreck the world completely (87:263).
I wished to obtain a clear statement of the rights of this
matter. Accordingly, I corresponded with specialists, who
eventually referred me to the works of James Clerk Max-
well, in one of whose papers I found the following statement
in support of Brown's position:
. . . The permanence of latitude essentially depends on the in-
equality of the earth's axes, for if they had all been equal, any altera-
tion of the crust of the earth would have produced new principal
axes, and the axis of rotation would travel round about those axes,
altering the latitudes of all places, and yet not in the least altering
the position of the axis of rotation among the stars (296:261).
For the word "axes" in the second line we may read "diame-
ters," and of course Maxwell is referring to the inequality
of the polar and equatorial diameters, that is, to the existence
of the equatorial bulge, to which, therefore, he directly at-
CAMPBELL'S MECHANISM 367
tributes the stability of the earth on its axis of rotation.
Maxwell, in the foregoing passage, suggests that in the ab-
sence of the equatorial bulge, any change in the crust (mean-
ing, it is clear, the creation of any protuberance or excess
weight at any point) would change the position of the planet
on the axis of rotation. Even before I located this passage in
Maxwell, a peculiar device designed by Brown had made this
principle clear to me by observation. This device consisted
of a globe mounted on three trunnions in such a way that it
could rotate in any direction. The globe was a perfect sphere
and had no equatorial bulge. It was suspended by a string
to an overhead point. To rotate this sphere, all that was
necessary was to wind it up and then let it go. Brown had a
weight attached to the South Pole of the sphere, and it was
observable that, as soon as the sphere began to rotate rapidly,
the weight was flung to the equator, where it stabilized the
direction of rotation as long as the speed of rotation was
maintained. Later Campbell made a larger model of Brown's
device, which I rotated unweighted, and I observed that it
had no stable axis of spin. Two motions were observable: a
rapid rotation, and a slow, random drifting. It was evident
that the mass of the sphere acted as a stabilizer of the speed
of rotation, but had no influence on its direction. This ex-
periment, strongly confirming Brown's claim, encouraged me
to persist until I could find positive theoretical confirmation
of the observation, which eventually I did in the works of
Maxwell.
I was amazed and chagrined in this connection to note a
phenomenon which, nevertheless, is as old as science itself.
The professors— most of them, at any rate—would not come to
see the device.
Perhaps I should describe this device in greater detail.
A trunnion is like a ring or a hoop, made of metal. A globe
is mounted in this trunnion on two pivots set into the ring
at points opposite each other (180 degrees apart). Then, if
the ring is held (as it often is on a model globe) by a pedi-
ment or stand, the globe will rotate. Its axis will be deter-
368 EARTH'S SHIFTING CRUST
mined by the fixed positions of the pivots set into the ring.
Now, if, instead of fixing the ring into a stand, or pedi-
ment, we set it into another, larger ring, by inserting two
pivots into the larger ring at two points at right angles to
those of the inner ring, we have an axis within an axis, and
the globe can be made to rotate in either direction. If a third
ring is used, then the globe has freedom of action in any
direction whatever.
There is still the problem of imparting momentum to this
globe. Since it has no fixed axis, this is a difficult problem.
Brown solved it by suspending the device to the ceiling by
a string attached to the outermost trunnion. This string
could be wound up by rotating the outermost trunnion in
one direction by hand for a while, just as a boy may wind
up the rubber bands used to give momentum to a toy air-
plane. Then, when the trunnion is released, the string un-
winds, putting the globe itself in rapid rotation, but a free
rotation, one not confined to a fixed axis.
In view of continued skepticism, I could not be entirely
satisfied by the Maxwell statement, supported though it
might be by the demonstration. Since I am not myself a
physicist, I felt it not unlikely that some persons would con-
clude that, in the first place, I had misunderstood Maxwell,
and that, in the second place, I was incapable of interpreting
correctly the evidence of my eyes. I therefore wished to ob-
tain an authoritative interpretation of Maxwell's statement,
and, accordingly, I wrote Dr. Harlow Shapley, the Director
of the Harvard Observatory, as follows:
After a year of intensive work with a group of people here, I have
concluded that the work we are doing is dependent upon a clear
answer to the question as to whether the geographical poles are stabi-
lized by the momentum of rotation of the earth, or solely by that of
the equatorial bulge. I have had discussions about this with Dr.
Adams of the Coast and Geodetic Survey, and with Dr. Clemence of
the Naval Observatory. They have given me references to the work
of Clerk Maxwell and others, without quite satisfying me. I am not,
of course, equipped to understand all of the technicalities, but I am
CAMPBELL'S MECHANISM 369
hoping that you can give me a steer in nontechnical terms on the gen-
eral concepts.
My hunch is that, contrary to a widespread impression, it is the
bulge alone that stabilizes the geographical poles. As I reason it out,
if the earth were a perfect sphere, the energy of its rotation, derived
from its mass in motion, would "stabilize" the speed of the rotation,
but would have no reference to its direction. If we suppose that some-
body could reach out from Mars with a pole, and give the earth a
strong push at an angle of 90° from the direction of rotation, the
earth would be shifted on the axis of rotation to an extent de-
termined by the ratio of the force of the push to the mass of the
earth. In fact, if the earth had no bulge, it would never have stable
poles, but would rotate every which way. . . .
If my view of the matter is sound, important consequences follow,
but I am not quite certain of the validity of my premises.
Dr. Shapley's reply, dated February 2, 1951, was, in part,
as follows:
Dr. [Harold] Jeffreys was fortunately here at the Harvard Ob-
servatory and I could turn over your inquiry to him. I now have his
reply. He says in effect that the fullest discussion of the points men-
tioned by you is in Routh's Rigid Dynamics, probably in volume I.
Most textbooks of rigid dynamics will have something about it. The
theory goes back to Euler. Really both the rotation and the equa-
torial bulge are needed to maintain stability. Without rotation the
body could be at rest at any position; with rotation but without the
equatorial bulge it could rotate permanently about an axis in any
direction. . . . (343).
With this statement I decided to rest content. It seemed to
me that Brown's position in the matter was correct. Maxwell
showed both by the use of his dynamical top and theoretically
what Brown showed by his device: that a rotating sphere
tends to throw the heaviest weights on its surface to the
equator of spin. Maxwell and, after him, George H. Darwin
recognized that the equatorial bulge of the globe stabilized
the direction of the earth's rotation just as a weight on the
surface of a model sphere would do when the sphere was
rotated rapidly.
Yet there is a distinct difference between the earth and
the model globe. The earth's approximately round shape is
370 EARTH'S SHIFTING CRUST
not due to the fact that it is a strong, rigid body, for it is not.
Its roundness is due primarily to the force of gravity, which
in fact holds the earth together. The earth as a whole is a very
weak body, and if it were not for the effect of gravity the cen-
trifugal effect of the rotation would disrupt the earth and
send all its component masses hurtling outwards into inter-
stellar space.
There is also a difference between the equatorial bulge of
the earth and a weight attached to the surface of a model
globe at its equator of spin. This difference consists in the
fact that the earth's equatorial bulge and the flattenings at
its poles have been produced by the yielding of the earth's
body in response to the centrifugal effect of its rotation. The
amount of the yielding has been determined by the ratio of
the forces of rotation and gravity. The shape of the earth
thus represents a balance of these two forces, a balance that
is perfect, theoretically, at every point of the earth's surface.
It therefore follows that any unit of material in this balanced
surface will be at rest. For this reason, such a surface has
been called an equipotential surface.
The balance of the forces of rotation and gravity at every
point of the earth's surface can be understood also in this
way. The shape of the earth, as we have pointed out, is ob-
late. This means that as you go toward the equator you are
getting farther from the earth's center. In a sense, therefore,
you are going uphill. Likewise, when you are going toward
the poles you are getting closer to the earth's center and
therefore you are going downhill. But we can all see that
it takes no more energy to move toward the equator than it
does toward a pole. Also, water in the ocean does not run
downhill toward the poles. The earth's surface acts as if it
were perfectly level. The reason for this is that as you go
toward the equator, going uphill, the centrifugal effect of
the earth's rotation increases just enough to compensate for
the gradient, while, if you move toward the poles, the cen-
trifugal effect declines in proportion. The forces of gravity
and rotation are therefore balanced, and no centrifugal e£-
CAMPBELL'S MECHANISM 371
feet will tend to propel a mass in this equipotential surface
toward the equator, and no gravitational effect will tend to
propel it toward the poles. The fact that the force of gravity
is absolutely much greater than the centrifugal effect of the
rotation is shown by the fact that the flattening of the earth
is very slight. The equatorial bulge amounts to 6.7 miles in
comparison with the earth's mean radius of 4,000 miles. This
is a ratio of only .017 per cent.
The past century has been notable for extensive studies
of the effects of gravity at the earth's surface. The theory of
isostasy has been developed, and the actually existing state of
balance of the surface features of the earth's crust has been
measured in various ways and for various purposes. As we
have seen, there are various difficulties with the theory of
isostasy, some of which may be soluble in terms of the theory
presented in this book. At the same time, but independently,
studies of centrifugal effects at the earth's surface have been
undertaken. Eotvos investigated the centrifugal effects that
would arise if a given mass had its center of gravity above
the equipotential surface. This could occur even with masses
in isostatic equilibrium. To visualize this case, we may take
the example of a block of ice floating in water.
Ice is lighter than water. When a block of ice falls into
a body of water it displaces its own weight of water, and
then floats with a tenth of its mass above the water level. It
is now in equilibrium, or in isostatic adjustment, even
though its upper part projects a considerable distance up out
of the water. This upper tenth, in the meantime, has dis-
placed air, not water. It is a solid mass of far greater density
than the air it has displaced. Its center of gravity, midway
between its summit and the water surface, is farther from
the axis of rotation of the earth than was that of the mass
of water it has displaced. Since points move faster with the
earth's rotation the farther they are from this axis, this mass
has now been given added velocity. Added velocity means
an increase in the centrifugal effect, and one not compensated
by gravity, since the amount of mass is the same as before,
372 EARTH'S SHIFTING CRUST
and therefore the effect of gravity at that point has not been
altered. A tangential component of this added centrifugal
momentum will tend to move this ice mass toward the
equator.
Eotvos applied this same principle to parts of the earth's
crust. We have seen that, according to the theory of isos-
tasy, mountains and continents are elevated above the ocean
bottoms because they are composed of lighter materials, and
they are considered to be ' 'floating" in an approximate gravi-
tational balance with the heavier crustal formations under
the oceans. Eotvos considered the centrifugal effects that
might arise from the elevations of the centers of gravity of
continental formations above those of the oceanic sectors of
the crust, and calculated them mathematically. He found
that the effects were comparatively slight. Attempts have
been made to account for the drift of continents through
these effects, but his calculations show they are too small to
have considerable effects. Since Eotvos' time, it has been
generally assumed that any centrifugal effects that were to be
considered in relationship to the earth's crust must be ef-
fects resulting from variations in the vertical position of cen-
ters of gravity of masses in gravitational balance, that is, ele-
vations of these centers above the equipotential surface, or
depressions of them below it, owing to differences in relative
density of the masses involved.
Let us now consider, in connection with this, the effect of
departures of given masses from the state of isostatic or gravi-
tational equilibrium. We have already seen that there are
remarkable departures from isostatic balance, some resulting
from deformities of the crust, and some, it seems, from the
accumulation of icecaps. In these irregularities in the dis-
tribution of matter, resulting from the limited failure of
isostatic adjustment, we must recognize the existence of an-
other surface of the earth, in contradistinction to the equipo-
tential or geoidal surface already mentioned. We may call
this surface the gravitational surface, or the surface of equal
mass. This is a real surface. It is not, however, the visible
CAMPBELL'S MECHANISM 373
surface. A high plateau may represent an area of deficient
mass, and an ocean basin may represent an area of excess
mass. We have seen that there are many oceanic areas that
show positive isostatic anomalies, or the existence of local
excesses of mass in the earth's crust. We can easily see the
distinction between the level equipotential surface of the
geoid, represented by sea level, and the surface of mass that
may deviate considerably from the level surface.
The mechanism for crust displacement presented in this
book depends upon recognition of the fact that distortions of
mass on the earth's surface, of whatever type, if they consti-
tute anomalous additions of mass at points on the earth's
surface, will give rise to centrifugal effects like the effect of
the mass attached to the surface of Brown's rotating model
sphere, in accordance with ordinary principles of mechanics,
and measurable by the standard formula for calculating
centrifugal effects.
An example may serve to illustrate the difference between
the surface of mass, which differs in elevation from place to
place, and the equipotential, geoidal surface. Let us take a
fictional case of a mass out of isostatic adjustment but with
its center of gravity below the surface of the geoid. Let us
suppose that under the bottom of the Atlantic Ocean we
have a slab of material ten times as dense as basalt, two thou-
sand miles long, one thousand miles wide, and forty miles
thick. The excess of mass in this slab, as compared with other
sectors of the crust, would be enormous, and gravity would
be greater at the surface. Consequently, the ocean level over
this area would be affected slightly, but the shape of the geoid
would not be significantly changed, and the sea level would
still represent an equipotential surface. The center of grav-
ity of the anomalous mass of high density would be depressed
far below sea level; it might be fifteen or twenty miles below
the geoidal surface. Now if the slab were of average density,
the depression of the center of gravity would mean an in-
verse Eotvos effect, that is, a poleward centrifugal effect, the
quantity of which, as we have seen, would be slight. But, now,
374 EARTH'S SHIFTING CRUST
to counteract this, the rotation of the earth, acting on this
mass of ten times normal density, would produce a centrifu-
gal effect ten times as great as the one normally balanced at
that point by the effects of gravity. Let us note the fact that
the assumption that this slab is not isostatically compensated
involves the consequence that the centrifugal momentum
resulting from it is not compensated.
The difference between an Eotvos effect and one produced
by an uncompensated mass may be illustrated in another
way. Let us return to our example of a mass of ice. Campbell
has suggested the example of an iceberg before and after its
separation from its parent, land-based icecap. It is assumed
that the icecap is uncompensated. The iceberg, breaking off
from the icecap, falls into the water. Before this event the
icecap, by assumption, is outside the equilibrium surface of
the geoid; the rotation of the earth acts upon it precisely as
the rotation of Brown's model sphere acts upon the weight
fixed to its surface.
But let us see what happens when the iceberg falls into
the sea. It now reaches gravitational equilibrium. It sinks,
and displaces its weight in water. It is now a part of the equi-
potential surface of the geoid (though the portion projecting
above sea level is not, and therefore exerts an Eotvos effect).
Now what is the quantitative relationship between the
Eotvos effect and the original centrifugal effect of the ice-
berg? It is plain that now nine tenths of the ice is within
the equilibrium surface. For this nine tenths of the mass the
equatorward centrifugal momentum produced by the earth's
rotation is precisely cancelled by the poleward component of
the force of gravity at that point, so that there is no net cen-
trifugal effect. Only one tenth of the ice remains to exert an
effect, and the quantity of this effect, furthermore, is de-
termined by the elevation of the center of gravity of this
tenth of the iceberg above sea level. But the elevation has
been enormously reduced. It has, in fact, been reduced to one
tenth of the elevation of the center of gravity before the fall
of the iceberg into the sea. Campbell has pointed out that,
CAMPBELL'S MECHANISM 375
as a result, the centrifugal momentum not compensated by
gravity has now been reduced to one one hundredth of the
quantity of the effect of the ice mass when it was totally
uncompensated.
It appears, therefore, that the question as to whether a
mass is in isostatic adjustment or not is the essence of the
matter. The icecap, if totally uncompensated, may produce
a centrifugal effect one hundred times the Eotvos effect for
the same mass; furthermore, it may be calculated by the
formula used by Campbell, with the reservation that a small
poleward component of gravity caused by the oblateness of
the earth and proportional to the degree of the oblateness
must be taken into consideration.
Let us attempt to define and clarify this poleward compo-
nent of the force of gravity, and to estimate its probable rela-
tive magnitude. It applies both to masses in equilibrium but
with elevated centers of gravity, and to any mass resting on
the earth's surface but uncompensated. Its effect will be
greater in the latter case than in the former. In both cases it
will tend to counteract the equatorward component of the
centrifugal effect of the icecap.
The poleward component of the force of gravity results
from the oblateness of the earth. It may be visualized as fol-
lows: if you should place a marble at the equator, and if the
rotation of the earth should be interrupted so that the earth
would be at rest, then the marble would tend to roll toward
one of the poles, because the poles are closer to the center of
the earth, and therefore downhill. As I have mentioned, this
applies both to masses out of isostatic equilibrium, and to
those in equilibrium, but with elevated centers of gravity
(that is, to masses standing higher because of their lesser aver-
age density). However, as I have pointed out, there will be a
quantitative difference between the poleward effects of gravity
in these two cases of about 100:1.
In both cases these effects would tend to counterbalance
the equatorward component of the total centrifugal effect of
the icecap. The question is: What proportion of the equator-
376 EARTH'S SHIFTING CRUST
ward effect would be thus counterbalanced? This is the crux
of the matter.
The answer to this problem may be found in the following
consideration. The force with which any object rolls down-
hill is proportionate not only to its weight but to the gradient
of the slope. On a flat surface the marble is at rest. It would
develop maximum momentum if it could fall straight down
toward the earth's center (if the surface were vertical). Be-
tween these extremes of zero and maximum momentum there
must be an even curve of increasing momentum with increas-
ing gradient. (It would follow, of course, that a sled would
develop twice the momentum if going down a hill twice as
steep.)
To apply this principle to the icecap, we may observe that
if there were no oblateness to the earth, there would be no
poleward component of gravity. If, on the other hand, the
oblateness were increased to the point where the icecap could
fall straight down, it would develop maximum momentum,
the product of its velocity and of its weight. Between these
extremes, the poleward momentum would be proportional to
the gradient. We have seen, however, that this gradient
amounts to only .017 per cent. It follows from this that the
poleward component of gravity acting on the icecap will be
.017 per cent of the tangential component of the centrifugal
effect of the icecap. This of course is a relatively negligible
quantity.
It may be objected that in this discussion we have offered
no mathematical calculations in support of the positions taken,
and that therefore we have no quantitative basis for our the-
ory. This is, however, a misunderstanding. It is essential, be-
fore mathematical computations are made, to understand the
assumptions on which they are based. In our correspondence
we have more than once received communications in which
the authors have indirectly or directly stated that the question
as to whether a given mass was or was not isostatically com-
pensated was irrelevant. It has seemed to us, on the other hand,
that the actual balanced surface or shape of the earth as de-
CAMPBELL'S MECHANISM 377
termined by the balance of gravity and the centrifugal effect
of the rotation— that is, the geoid, or the equipotential surfaces
—while perfectly valid as an assumption for many calcula-
tions, was irrelevant for our problem. We feel it must be
conceded that if the conformity of the earth's materials in
general to the balance of the two forces of gravity and rotation,
so as to create the oblate shape of the earth— the geoid— is im-
portant, the failure of some of the materials to conform to
this shape is also important. By definition, a mass that is not
isostatically compensated fails to conform to this shape. Thus
the real surface of mass differs from the geoid, and cannot
be called an equipotential surface. We feel that the real "sur-
face of mass" of the earth cannot be disregarded.
In this situation equations are of no use. They will not help
us attain clarity. What is needed instead is a re-examination
of the assumptions on which equations have been made. This
is an intellectual problem of the logical development of ideas,
and corresponds to the process advocated by Maxwell as supe-
rior, in some situations, to calculations. Discussing the intri-
cacies of the mechanics of rotation before the Royal Society,
Maxwell remarked:
... If any further progress is to be made in simplifying and
arranging the theory, it must be by the method that Poinsot has re-
peatedly pointed out as the only one that can lead to a true knowl-
edge of the subject— that of proceeding from one distinct idea to an-
other, instead of trusting to symbols and equations (296:24811).
Let us remember that the author of this remark was one
of the greatest mathematical physicists of all time. As such,
he understood the limitations of mathematics, of which the
most essential is that all calculations must be based in the
last analysis on assumptions that consist of clear ideas, logically
expressible in words.
I do not wish to have it seem, however, that I am conced-
ing the point that Mr. Campbell and I have not provided
quantitative solutions. On the contrary, I believe that, on the
basis of the assumptions discussed above, Mr. Campbell has
provided sound and adequate (though approximate) quanti-
378 EARTH'S SHIFTING CRUST
tative estimates for the equatorward component of the cen-
trifugal effect of the icecap, and furthermore, that he has
indicated the correct order of magnitude of the bursting
stresses that may be produced in the crust.
XII : CONCLUSION
i. Looking Forward
It is said that a sound scientific hypothesis should have the
character of predictability. "Predictability" is said to apply
to a hypothesis if the hypothesis predicts the discovery of new
facts that later are actually discovered. An example of pre-
dictability of this sort was the discovery some years ago of
Pluto as the result of calculations based on the theory
of gravitation. Our theory has repeatedly shown that it pos-
sesses this sort of predictability. On one occasion Campbell
worked out, from purely theoretical considerations, the pat-
terns of crustal fractures that would be formed by a dis-
placement. At the same time, in a different city and entirely
independently of him, I was discovering, in the works of W.
H. Hobbs, geological evidence showing that fracture pat-
terns of precisely this kind actually existed in the rocks.
Only later did we compare results. If I had started with his
drawings and used them to guide my research in the field,
I would have found approximately the fracture patterns that
he predicted, and I would have found them sooner. On
another occasion when, in 1951, radiocarbon dates showed
the very recent end of the North American ice sheet, I
reached the conclusion from the theory that the begin-
ning of that glaciation must have been quite recent, and
much more recent than generally believed. At that time
this conclusion could not be tested, because the range o£
the radiocarbon method was not great enough. However,
I was aware of the fact that several scientists were work-
ing on the problem of extending the range, and I confidently
looked forward to a confirmation of the theory when and if
the range was extended. I had to wait only until 1954, when
Horberg, as already mentioned, published results showing
380 EARTH'S SHIFTING CRUST
that the icecap had entered Ohio only 25,000 years ago.
Again and again we have had experiences similar to this.
Campbell has, in fact, suggested that the theory may have
economic importance because of the fact that it may give
us a tool through which we may attain more reliable infor-
mation about the hidden structures of the earth's crust, and
thus be able to locate valuable minerals. It seems to me
quite possible that his hope will eventually be realized.
Our theory appears to have another kind of predictability.
It is possible that it can tell us something about the rela-
tively near future of the earth. The evidence appears to sug-
gest that displacements have occurred at short intervals.
Since what has happened in the past may be expected to hap-
pen in the future, it is quite reasonable to ask when another
movement may be expected. There are a number of factors
that bear on this, and they are worth discussing even though,
when we get through, we may carry away the feeling that our
speculations may contain more imagination than substance.
It would appear from the evidence I have presented that
the intervals between the beginnings of the last three dis-
placements were about 40,000 years in length. It seems, also,
that the last movement began between 26,000 and 17,000
years ago. If these assumptions are correct, and if the average
of these movements holds for the future, it seems that the
next displacement of the crust should not be expected for
another 10,000 or 15,000 years. While this is a reassuring
thought, it should be kept in mind, however, that there are
a number of unknown factors in the situation, and that there
is no reason to believe that the average of the last three dis-
placements tells us anything about the limits of variation in
the periods between displacements. On the contrary, the
conclusion to be reached from the investigation completed in
this book is that the periods between displacements may
vary considerably.
A number of factors favor a movement somewhat sooner
than the time indicated by the average of the last three dis-
placements. Among these, I may mention the fact, empha-
CONCLUSION 381
sized by Brown, that the present Antarctic icecap is larger
than the last North American icecap. If Campbell's calcula-
tions are close to the truth, it seems that the bursting stresses
in the crust may now be close to the critical point, from this
source alone. Yet there is also a possibility that the centrifu-
gal effect of the Antarctic icecap may at the present time be
supplemented by another significant centrifugal effect cre-
ated by the icecap in Greenland. It is true that the Greenland
cap is much smaller than the one in Antarctica, but, on the
other hand, its center is much farther from the pole. For
this reason it could conceivably have an important centrifu-
gal effect. Its position on the meridian is such that any un-
compensated mass would add to rather than counteract the
effect of the Antarctic cap; the two icecaps are, so to speak,
in tandem.
In recent years a French polar expedition has taken many
gravity readings across the top of the Greenland icecap. The
purpose of these readings was to assemble data for a deter-
mination of the state of isostatic adjustment of the Greenland
cap. The results of this piece of research are instructive for
the whole subject of isostasy. They can be read two ways. On
the one hand, the gravity data when reduced according to
one of the formulas in common use— the Faye-Bouguer— -
showed an enormous excess of mass in Greenland (441:60-
61); on the other hand, the same data, when reinterpreted
differently, resulted in a finding of good isostatic adjust-
ment. It is important to realize that the different methods
of reducing gravity data are based on varying assumptions
regarding the deeper structure of the earth's crust, and that
these assumptions are not subject to direct confirmation.
Daly at one time remarked that he did not believe that any
of the different methods of evaluating gravity data came very
near the actual truth. It is reasonable to think that the se-
lection of assumptions in this field may be influenced by a gen-
eral belief in the soundness of isostasy, and that this general
belief will lead to a preference for those assumptions that
result in findings of close isostatic adjustment. It is perhaps
382 EARTHS SHIFTING CRUST
on account of this that Einstein regarded the theory of isos-
tasy as itself unreasonable (128). According to our theory,
Greenland possibly was deglaciated during the period of the
Wisconsin icecap in North America, and therefore the ice-
cap there may be recent, and isostatic adjustment poor,
There are a few indications that the pressure of the Ant-
arctic cap (possibly reinforced by the Greenland cap) has
already begun to disturb the stability of the earth's crust.
These consist of recent seismic movements.
In the study of earthquakes, specialists have distinguished
between them not only according to their scale but also by
a qualitative difference that appears to exist between those of
minor and those of major magnitudes. Minor earthquakes,
which occur daily in considerable numbers, are considered
to be of local origin. They are merely episodes in the per-
petual process of adjustment of strains in the earth's crust
arising from local causes.
Some of the major earthquakes, on the other hand, are
considered to be qualitatively different. Benioff, for example,
suggests that these major earthquakes are not related to local
causes of any sort, but result from the operation of what he
calls "world-wide stress systems" (29)— in other words, from
pressures applied to the earth's crust as a whole. So far as I
know, no geologist has advanced an explanation for these
world- wide pressures; it seems quite possible that they may
be related to the icecap pressure that, according to our view,
has been increasingly exerted on the crust for thousands of
years.
Benioff draws attention to a fact that appears to confirm
this supposition. He points out that in recent decades there
has been an increasing tempo of major earthquakes; they
appear to be coming closer together and increasing in vio-
lence. He cites especially the great quakes of 1904, 1924,
1935> 194°> and 1950 (29:335). If the Antarctic icecap is the
major cause of these quakes, we can understand the increase
in their frequency and intensity, which may result either
from the increase of the quantity of Antarctic ice or from
CONCLUSION 383
the progressive weakening of the crust under the repeated
major shocks.
Some further confirmation of this suggestion may be found
in some specific features of the two greatest of the major
earthquakes, those of eastern India in 1897 and in 1950. The
earlier of these was a cataclysm that involved hundreds of
thousands of square miles. The later one was still more vio-
lent, in line with the observation made by Benioff. The
reader may note, by glancing at the globe, that the area in
which these two quakes occurred lies almost on the meridian
of 96° E. Long., which, it appears, is the meridian of direct
thrust of the Antarctic icecap. According to our theory, this
is the meridian along which the gradually increasing thrust
of the Antarctic icecap has been exerted for thousands of
years. Let us note the fact that Assam lies across the equator
from the South Pole, and that the thrust of the icecap would
tend to push the area toward the north, or poleward, so that,
because of the shape of the earth, the result would be com-
pression of the crust in that area. Now it is not unreasonable
to suppose that during several millennia the pressure from
Antarctica may have resulted in some elastic yielding of the
crust along the meridian, with consequent concentration of
compressive stresses in that area.
I cannot say that the constant pressure of the Antarctic
icecap, operating on the crust in the same direction for ten
thousand years or more, and amounting to several times
a million times a million tons, definitely did cause some
yielding of the crust in that direction, because I do not know,
but I know what would have happened if there were some
yielding. Yielding, at the latitude of Assam, to a pressure
directed from the south would mean compression of the
crustal material between lateral pressures, because of the
lesser circumference of the globe as one goes north. If we
suppose only a very slight yielding of the crust along the
meridian (amounting to only a few feet) the pressures so
produced would be very great. An explosive situation would
exist because rock is not very compressible. The forces would
384 EARTH'S SHIFTING CRUST
have to express themselves somehow. There would be no
place to go but up. A striking confirmation of this may be
found in the extraordinary fact that Mt. Everest and pos-
sibly much of the Himalayan range appear to have been
raised from 100 to 200 feet by the gigantic earthquake of
Now we learn from Daly that gravitationally the Hima-
layas are already too high. They are, or were before the
earthquake, over 700 feet higher than they should have
been for good isostatic adjustment. Earthquakes are generally
supposed to perform the function of enabling the crust to
adjust to the force of gravity. If an area stands too high,
earthquakes occur during a process of settling down to
equilibrium. If an area is too low, earthquakes may occur as
it is rising. But what shall we say about an earthquake that
finds an area already too high, and shoves it up further?
This earthquake is not behaving according to the rules. It
is not tending to establish the stability of the crust, but rather
is exposing the crust to a situation of increased strain after
the quake.
But most important of all, where could the compressive,
horizontally directed force have come from to cause this
earthquake? The best reason for putting forth the claims of
the Antarctic icecap is that, so far, no one has produced a
more reasonable suggestion. It is interesting that the editors
of Life, in their illustrated account of the great quake in
Assam, called it "the most mysterious earthquake of mod-
ern times/'
There are a few additional items that appear to fit into
this picture. In the very year in which the Assam earthquake
occurred (1950) another great earthquake on the same merid-
ian, but on the opposite side of the earth, virtually destroyed
the city of Cuzco. Also near the same meridian, in Mexico,
we have recently seen the rapid creation of the great new
volcanic mountain of Paricutfn, an event that Campbell
ascribes to the effects of the increasing bursting stress on the
crust in the earth's equatorial bulge. Finally, it may be worth
CONCLUSION 385
while to mention Ewing's recent discovery of a world-wide
system of great submarine canyons, along which the crust is
technically active. Observers have suggested that these can-
yons are still widening. Breen has pointed out that their pat-
tern (not yet fully established) is consistent with the effects
of a force attempting to pull the Western Hemisphere south-
ward (44).
I am aware that the items that I have mentioned above
may all be explained someday according to other principles,
and may in fact have nothing to do with centrifugal effects
from Antarctica. However, I feel that a definite chance exists
that the phenomena may be related, and that they may indi-
cate that beginning of a crust displacement is not remote. The
question therefore arises as to whether, in case of another
displacement, it is possible to predict anything about it in
detail. Among the questions to which answers may be sought
are those of the precise direction the displacement may take,
and the total distance it may cover.
As to the first question, our theory offers us the basis for
a reasonable estimate. If our finding of the location of the
center of mass of the Antarctic icecap is correct, and if we
assume that no other centrifugal effects from anomalies in
the crust will be acting to deflect the motion, we may expect
the next displacement to be in the direction of 96° E. Long,
from the South Pole. This would involve another southward
displacement of the Western Hemisphere, together with an-
other northward displacement of East Asia.
A guess as to the magnitude of the next displacement re-
quires the correct assessment of a number of rather impon-
derable factors. We should expect the crust to continue to
move until the Antarctic icecap was largely destroyed. This
might take longer than it did in the case of the North Amer-
ican icecap, because the Antarctic icecap is larger. On the
other hand, it could take less long, because in the case of
Antarctica there is no land available for the rearward build-
up of the icecap as it moves into the lower latitudes, such as
seems to have occurred in North America. Perhaps we shall
386 EARTH'S SHIFTING CRUST
have to be satisfied, for the present, with the guess that the
next displacement may be of roughly the same magnitude as
the last one.
If these guesses turn out to be correct, the next North Pole
will be in the vicinity of Lake Baikal, in Siberia. North
America, moving southward into the tropics, will subside
some hundreds of feet relatively to sea level, and the ocean
will occupy the river valleys and will divide the continent
into several land areas. India will move northward out of the
tropics, and since there will be no land to the south to pro-
vide a refuge for the fauna and flora, we shall have to expect
the extinction of many species of animals and plants now
confined to that country. Many other consequences may be
unpredictable. The gradual climatic changes due to changing
latitude will be accompanied by numerous sudden, violent,
and destructive climatic changes due to volcanism.
2. A General Summary
In this book I have presented a highly detailed mass of mate-
rial, and I have sought to relate it to a single, essentially
simple hypothesis. It now remains to summarize the evi-
dence, and the argument for the hypothesis.
We have seen that the problem of the geographical stabil-
ity of the poles has long been a vexatious matter for science.
From time to time theories of polar shift have been advanced,
supported by large quantities of evidence, but the proposed
mechanisms have been found defective, and in consequence
the theories have been rejected. The failure of the theories
has led, in the following years, to neglect of the evidence, or
to its analysis in accordance with theories conforming to the
doctrine of the permanence of the poles. Although all the
older theories of polar change, including that of Wegener,
have been discredited, the evidence in favor of polar change
has constantly increased. As a consequence, many writers at the
CONCLUSION 387
present time are discussing polar shift, but none of them has
as yet suggested an acceptable mechanism.
The general evidence for displacements of the crust is ex-
ceedingly rich. In turn, the assumption of such displacements
serves to solve a wide range of problems, such as the causes
of ice ages, warm polar climates, mountain building; it pro-
vides a mechanism that may account for changes in the eleva-
tions of land areas and in the topography of the ocean floors;
it also provides a basis for the resolution of conflicts in iso-
static theory. For the period of the late Pleistocene, the theory
permits the construction of a chronology of polar shifts, with
three successive tentative polar positions in Alaska, Green-
land, and Hudson Bay preceding the present position of the
pole. The evidence for the location of the Hudson Bay
region at the pole during the last North American ice age is
overwhelming, and this fact in itself provides the principal
support for the assumption of the earlier shifts. The tempo
of change indicated for the late Pleistocene is reflected in
evidence from earlier geological periods.
The theory is able to explain not only the general succes-
sion of climatic changes in various parts of the world in the
late Pleistocene; it can account also for the detailed history
of the last North American icecap. It can explain the fluctua-
tions of that icecap, its repeated retreats and readvances. It
shows that the effects of volcanism were directly responsible
for the oscillations. It shows also that these same effects,
added to the effects of gradual climatic change, were responsi-
ble for the widespread extinctions of species at the end of the
Pleistocene, and from this we may assume that the same
cause was responsible for numerous extinctions in earlier
geological periods. By providing a reasonable basis for the
assumptions of rapid climatic change and rapid topograph-
ical change (including the existence of former continents and
land bridges), the theory provides solutions for many prob-
lems in the evolution and distribution of species.
Our theory of displacement depends upon two assump-
tions, and on two only. One of these is that a continental ice-
EARTH'S SHIFTING CRUST
cap is largely or entirely uncompensated isostatically. The
other assumption is that at some point below the crust a weak
layer exists that will permit the displacement of the crust
over it. The first assumption is capable of verification, and
may even be verified in the course of the current Geophysical
Year. This will depend, however, on whether the new gravity
data that are to be collected during this year are reduced by
formulas based on correct assumptions. There is no present
prospect of direct verification of the second assumption.
However, the body of geological evidence presented in this
book provides very strong indirect support for both these
assumptions.
As to the mechanics of crust displacements, Campbell has
provided the necessary constructions. To some, the simplicity
of his thought may be unnerving, but I feel assured that in
the end this simplicity itself will be the justification for re-
posing wide confidence in this theory. For it appears that no
recondite principle can vitiate it. Who can argue with for-
mulas so simple that a high school student can, and usually
does, master them?
In addition to the support provided by evidence from the
field, our theory receives support from logic. It has been
recognized that one characteristic of sound new theories is
the simplicity of their basic assumptions, and another is their
capacity to explain a greater number of facts or a greater
range of problems than previous theories. It was the sim-
plicity of this theory that first aroused the interest of Einstein,
in whose philosophy of science simplicity was a prime con-
sideration. It appeared to him also that it might explain a
far greater number of facts than were explainable by the
various theories that have been produced to explain the lead-
ing problems of the earth separately.
I shall have to admit that the full development of the im-
plications of crust displacements, for all the affected fields,
has carried me much further than I originally expected.
When I resurvey the structure that has now been erected on
the basis of the simple basic theory, I feel exactly as Sir James
CONCLUSION 389
Frazer, author of the Golden Bough, felt at the end of his
protracted labors, and I cannot do better than conclude this
volume with his words:
Now that the theory, which necessarily presented itself to me at
first in outline, has been worked out in detail, I cannot but feel that
in some places I may have pushed it too far. If this should prove to
have been the case, I will readily acknowledge and retract my error
as soon as it is brought home to me. Meanwhile, my essay may serve
its purpose as a first attempt to solve a difficult problem, and to bring
a variety of scattered facts into some sort of order and system. (The
Magic Art)
"But when you have the truth, everything fits.
I think that's the main test of truth. It fits, it
makes a harmony, one pattern all through. . . ."
E. R. Punshon, Information Received
(Penguin Books, 1955)
APPENDIX
Letters from Albert Einstein and George Sarton
A. Einstein
112 Mercer Street
Princeton, N. J.
November 24, 1952
Mr. Charles Hapgood
2 Allerton Street
Provincetown, Mass.
Dear Sir:
I have read already some years ago in a popular article about the
idea that excentric masses of ice, accumulated near a pole, could pro-
duce from time to time considerable dislocations of the floating rigid
crust of the earth. I have never occupied myself with this problem but
my impression is that a careful study of this hypothesis is really de-
sirable.
I think that our factual knowledge of the underlying facts is at pres-
ent not precise enough for a reliable answer based exclusively on
calculations. Knowledge of geological and paleontological facts may be
of decisive importance in the matter. In any case, it would not be justi-
fied to discard the idea a priori as adventurous.
The question whether high pressure may not be able to produce
fusion of nuclei is also quite justified. It is not known to me if a quanti-
tative theory has been worked out by astrophysicists. The action of
pressure would not be a static effect as classical mechanics would sug-
gest, but a kinetic effect corresponding not to temperature but to de-
generacy of gases of high density. You should correspond about this
with an astrophysicist experienced in quantum theory, f.i. Dr. M.
Schwarzschild at the Princeton University Observatory.
Sincerely yours,
(Signed) A. Einstein
APPENDIX
Princeton,
May 8, 1953
Dear Mr. Hapgood,
I thank you very much for the manuscript that you sent me on May
3rd. I find your arguments very impressive and have the impression that
your hypothesis is correct. One can hardly doubt that significant shifts
of the crust of the earth have taken place repeatedly and within a short
time. The empirical material you have compiled would hardly permit
another interpretation.
It is certainly true, too, that ice is continually deposited in the polar
regions. These deposits must lead to instability of the crust when it is
sufficiently strong not to constantly keep in balance by the adjustment
of the polar regions.
The thickness of the icecap at the polar regions must, if this is the
case, constantly increase, at least where a foundation of rock is present.
One should be able to estimate empirically the annual increase of the
polar icecaps. If there exists at least in one part of the polar regions a
rock foundation for the icecap, one should be able to calculate how
much tune was needed to deposit the whole of the icecap. The amount
of the ice that flowed off should be negligible in this calculation. In this
way one could almost prove your hypothesis.
Another striking circumstance appears in connection with the ellip-
ticity of the meridians. If according to your hypothesis an approximate
folding of the meridional volume takes place, that is, folding of a
meridional volume within an equatorial volume (which is considerably
larger), this event will have to be accompanied by a fracture of the hard
crust of the earth. This also fits in very well with the existing phe-
nomena of the volcanic coastal regions with their mainly north-south
extension and the narrowness in the east-west direction. Without your
hypothesis one could hardly find a halfway reasonable explanation for
these weak spots of the present-day crust of the earth.
Excuse me for not writing in English. My secretary has been away
for some time, and "spelling" makes frightful difficulties for me.
With sincere respect and kind regards,
Yours,
(Signed) A. Einstein
(Translated by Use Politzer)
392 EARTH'S SHIFTING CRUST
5 Channing Place,
Cambridge, Mass.,
Tuesday '55 06.07
Dear Mr. Hapgood,
I have read your lecture at the AMNH, the discussion which followed
and the Einstein documents, with deep interest. I really think that you
are on the right track but have no authority to express a more definite
opinion. It is clear that the only opinions which matter are those which
are the results of independent studies by competent specialists.
The combination of ideas is so new that the history of science has
nothing to contribute to its understanding. The fact that there have
been earlier theories like those of Wegener, Kreichgauer and Vening
Meinesz simply proves that some meteorologic and geologic problems
had to be solved, and exercised the minds of men of science. What you
need is not historical facts, but physical ones, and mathematical de-
velopments.
With every good wish
(Signed)
George Sarton
GLOSSARY
ANOMALY, Positive: An excess of mass at a point on the crust, as com-
pared with the average distribution of mass.
Negative: A similar but opposite condition, in which there is a
local deficiency of mass.
ANTICLINE: An archlike folding of rocks or rock strata so that the
lower beds or strata are enclosed in the upper.
ARCHAEOCYATHIDAE: A fossil sponge, at one time supposed to be
a fossil coral.
ASTHENOSPHERE: A layer of material below the crust; assumed to
be weak because of heat and pressure.
BASEMENT ROCKS: Rocks of great obscurity and complexity lying
beneath the upper rock layers; thus, the lowermost rocks of the
known series.
CENTRIFUGAL FORCE: The force tending to throw a body away
from the center, in a straight-line direction of flight.
DECIDUOUS TREES: Trees having seasonally falling foliage (oak,
elm, etc.) as contrasted with evergreens, having constantly renewed
foliage (pine, etc.).
DIASTROPHISM: The process, or processes, by which major features
of the crust are formed through deformation, such as faults, plateaus,
etc.
ECOLOGICAL: Pertaining to the mutual relationship between organ-
isms and their environment. An ecology is the place-relationship of
life forms in their environment.
EPEIROGENESIS (EPEIROGENY): A grander form of diastrophism,
forming the broader features of crustal relief, such as continents,
ocean beds, etc.
EPICONTINENTAL: Pertaining to regions along the continental shelf.
EUSTATIC: Pertaining to a land area which has not undergone eleva-
tion or depression.
GEOID: The figure of the earth (an oblate sphere) with the average sea
level conceived of as extending throughout the continents.
GEOSYNCLINE: A great downward flexing of the crust.
GRAVITY, Center of: An imaginary point at which, for reasons of
computation, the entire weight or mass of a body is imagined to be
concentrated.
HORSE LATITUDES: A belt in the neighborhood of 30° N. or S. Lat,
characterized by high pressure, calms, and baffling winds.
394 EARTH'S SHIFTING CRUST
HYDROSTATIC: Pertaining to pressure and equilibrium of liquids.
IGNEOUS ROCKS: Rocks which have cooled and solidified from a
molten state.
INSOLATION: Solar radiation received by the earth. The insolation
curve represents the combined effects on mean world-wide tempera-
tures of various astronomical factors, such as precession and varia-
tions of the orbit of the earth about the sun.
ISOSTASY: The definition is discussed in the text: Chapter VI.
LITHOSPHERE: The outer shell of the planet. It is composed of rocks
and the products derived from them by erosion, etc., such as gravels,
soils, and the like. The crystalline, solid lithosphere is assumed to be
between 20 and 40 miles thick. (Also called crust.)
LOAD, Negative: A deficiency of matter at a given point on the crust;
considered negative because it results in a pressure from within, as
a result of the tendency to achieve hydrostatic balance.
Positive: A local excess of mass.
MAGMA: Molten rock material within the earth. When cooled and
crystallized into solid form it yields the so-called igneous rocks (q.v.).
MASS: A measure of the amount of matter in a body.
MASS, Center of: Point at which the mass is assumed to be concen-
trated; for computational purposes.
METAMORPHIC: Altered; applied to rocks or rock strata that have
been physically changed by heat or other means.
MILLIGAL: A thickness of ten meters of granite; the effects (gravi-
tational) produced by such mass.
MUTATION: A sudden variation in the characteristics of a life form
as compared to those of its progenitors.
NEBULAR THEORY: A theory of the origin of the solar system, ac-
cording to which a gaseous nebula coalesced and cooled to form
compacted centers which then further contracted to form the
planets.
OOZE: A soft deep-sea deposit composed of shells, debris, meteoric
dust, etc. Argillaceous ooze is a clayey type.
PLANETESIMAL: A small, solid planetary body having an individual
orbit about the sun.
PLANETESIMAL HYPOTHESIS: A theory of the origin of the solar
system supposing that the planets were formed by collision and
coalescence of planetesimals and thus have never been wholly
molten.
PLICATION: Folding into layers or strata.
PRECESSION: The wobbling of the axis of the earth, making the pole
describe a circle as the planet spins.
RADIATION, Adaptive: The production of a diversified fauna as the
result of the availability of new ecological spaces. New faunas re-
GLOSSARY 395
suit from the adaptation of an original stock to the new environ-
mental opportunities for living space.
SIAL: Silicon-aluminum rocks.
SIMA: Silicon-magnesium rocks.
STRANDLINE: A line marking a fossil seashore.
STRATIGRAPHIC: Pertaining to the arrangement of rock strata.
TECTONIC: Pertaining to rock structures resulting from deformation
of the crust.
TURBIDITY CURRENTS: Submarine currents caused by slumping
of deposits along continental margins. These currents carry sedi-
ments with them.
UNCOMPENSATED WEIGHT: The weight of a crustal formation not
isostatically adjusted. It thus constitutes a positive anomaly (q.v.).
UNIAXIAL: The condition of having only one axis, as a sphere.
VARVES: Annual deposits of sediment. These can be counted to de-
termine annual shorelines of old lakes.
VIRENZPERIOD: A period in the history of a life form in which it ex-
periences an explosive evolution and proliferation.
VISCOSITY: The quality of being able to yield to stress or of being
able to flow; the measure of such a property.
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428a. Twenhofel, W. H., ed., "Environmental Significance of Dwarfed
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4 28b. Twenhofel, W. H., Principles of Sedimentation. New York and
London, McGraw-Hill, 1939.
429. Umbgrove, J. H. F., "Recent Theories of Polar Displacement."
American Journal of Science, v. 224, No. 2 (Feb., 1946).
430. Umbgrove, J. H. F., The Pulse of the Earth, 2d ed. The Hague,
Martinus Nijhoff, 1947.
431. "U. S. Geological Survey Radiocarbon Dates I." H. E. Suess,
Science, v. 120, No. 3117 (Sept. 24, 1954).
432. "U. S. Geological Survey Radiocarbon Dates II." Rubin, Meyer,
and Suess. Science, v. 121, No. 3145 (April 8, 1955).
433. "U. S. Geological Survey Radiocarbon Dates III." Science, v. 123,
No. 3194 (March 16, 1956).
434. "University of Michigan Radiocarbon Dates I." H. R. Crane.
Science, v. 124, No. 3224 (Oct. 12, 1956).
436. "University of Pennsylvania Radiocarbon Dates I." Science, v.
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437. Urey, Harold C., "Measurement of Paleotemperatures and Tem-
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438. Urey, Harold C., The Planets, Their Origin and Development.
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439. Urry, W. D., "Radioactivity of Ocean Sediments VI." American
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440. Urry, W. D., "The Radioelements in Non-Equilibrium Systems."
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456. Wilson, J. Tuzo, "The Origin of the Earth's Crust." Nature, v.
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457. van Woerkom, A. J., in Shapley, Climatic Change.
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460. Wright, G. F., Greenland Ice Fields and Life in the North At-
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1937-
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1922.
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Science, v. 118, No. 3052 (July 3, 1953).
465. "Yale Natural Radiocarbon Dates II." Preston, Person, and
Deevey. Science, \. 122, No. 3177 (Nov. 18, 1955).
INDEX OF NAMES
Abrons, Stanley Howard, 8
Akimoto, 308
Alexander the Great, 52n.
Almond, Mary, 33
Anderson, W., 221-22
Antevs, Ernst, 195, 211-13, 216, 224
Anthony, Harold, 7
Archer, William, 6
Argyris, Thomas S., 230
Arrhenius, Gustav, 303
Bain, George W., 32, 37, 66, 71-73,
177-78, 197
Ball, Robert, 39
Barghoorn, 61-63, 68, 315
Barnes, Joseph, 240
Barrell, 89, 156-57
Bell, Robert, 233
Belov, N. A., 235
Benedict, F. G., 233
Benfield, A. E., 117
Benioff, H., 382
Bergquist, N. O., 204
Berry, 68-69
Birdseye, Clarence, 240, 242
Bishop, Mrs. Helen, 7
Bishop, Sherman C., 260-64
Blanchard, Jacques, 32, 309
Bowen, 11
Breen, Walter H., 7, 8, 385
Brewster, E. T., 140—41
Brice, J. C., 8
Bridgman, Percy L., 7, 21, 187,
189, 191 > 35<>, 357' 358
Brooks, C. E. P., 52, 59, 64, 68, 137,
140, 224, 255, 309, 310
Broterus, 248
Brouwer, Dirk, 6, 17, 43
Brown, Hugh Auchincloss, 6, 15-
19, 170, 365-68, 373, 374, 381
Bruckner, 281, 282
Bucher, Walter H., 7, 84, 125, 227
Buker, Errol, 6, 19, 343
Bullard, E. C., 80
Byrd, Richard Evelyn, 59, 168
Campbell, James H., 6, 7, 13, 19—
21, 73, 90-105, 108, no, 111,
114-15, 123, 159, 171, 197, 209,
237» 34o-78» 379~8l» 384» 388
Caster, K. E., 28
Chaney, Ralph W., 27, 69
Charlesworth, J. K., 35, 298
Clegg, J. A., 33
Clemence, G. M., 6, 368
Clisby, Katharyn H., 290
Cloos, Hans, 9, 10, 143-44
Colbert, 62, 63, 66, 67, 68
Coleman, A. P., 11, 34-38, 43, 67,
68, 136, 170, 203-4, 219, 263,
272, 278, 308, 311, 321, 366
Columbus, Christopher, 52n.
Commoner, Barry, 8
Croll, James, 279, 280, 310, 311
Cruzen, Rear Admiral, 166
Dachille, Frank, 32, 193
Daly, R. A., 9, 10, 21, 30, 35, 79,
8l, 112, 117, 119, 132-33, 150,
151-52, l6o, l6l—62, 172-77,
181-83, l86> 187-89, 94> 221,
357> 38l> 384
Dana, J. B., 89
Darwin, Charles, 225, 315, 316,
325, 327-28, 335, 338
Darwin, George H., 25, 32, 369
422
EARTH'S SHIFTING CRUST
Davies, O., 39
Day, A. L., 112, 114
de Geer, Ebba Hult, 207, 211
de Geer, Gerard, 46, 211
Deininger, Mrs. Whittaker, 20
DeRance, 64, 136
de Vries, Hugo, 316
Dickerson, 223
Digby, Bassett, 239, 240
Dillon, Lawrence, 195-96
Dobrolet, Walter, 6
Dobzhansky, Theodosius, 318
Dodson, Edward O., 136, 271, 305,
3l8> 3*9» 336
Dorf, Erling, 332
Dorsey, H. G., 255
Dougherty, Lyman H., 60
Drayson, A. W., 43, 45
Dufty, Mrs. Maely, 8
du Toit, A. L., 37
Dutton, Clarence, 83-84, 102
Eardley, 115
Eddington, A. E., 70, 197
Einstein, Albert, i, 6-7, 8, 20, 55,
114, 170-71, 172-74, 179, 185,
186, 194-95* 345» 35<>> 351* 357*
361-65, 382, 388, 390, 391
Emiliani, Cesare, 43, 201, 202, 277,
282, 294, 300, 309
Eotvos, 357, 37 1-75
Ericson, David B., 7, 55, 74, 270,
293, 300
Euler, Leonhard, 369
Ewing, Maurice, 109, 141, 358
Falconer, 233
Feilden, 64, 136
Finnegan, H. E., 222
Firbaz, Franz, 207
Fisk, H. N., 218-19
Flint, Richard Foster, 54, 145, 201,
211, 255, 272, 278, 287
Forrest, H. Edward, 297, 299
Frankland, John M., 7, 118, 190,
35°> 353' 359
Frazer, James G., 389
Geikie, Archibald, 189-90, 225,
279
Gidley, James William, 308
Gilluly, 131, 221
Gilman, Coburn, 8
Godwin, Harold, 219
Gold, T., 32, 197, 355
Goldring, Winifred, 66
Goldschmidt, Richard, 319, 320
Grabau, Amadeus W., 125-26
Graham, J. W., 32
Grand, Mary Garrison, 7, 361
Gregory, J. W., 136
Gutenberg, Beno, 9, 11, 30, 32, 35,
63, 79-80, 87, 88, 116, 118, 120-
23, 137, 162-63, 189, 226, 354
Hackett, Chauncey, 7
Haldane, J. B. S., 318
Hall, 89
Halle, T. B., 223
Hansen, L. Taylor, 30, 207
Hapgood, Mrs. Norman, 8, 245
Harris, Herbert, 240
Hartnagel, C. A., 260-64
Heiskanen, 182
Henry, Thomas R., 9, 59, 60, 166-
67
Herz, F. F., 240, 248
Hibben, Frank C., 7, 9, 207, 227,
266-69, 271
Hillaby, John, 218-19
Hobbs, William H., 12, 104, 105,
106, 113-14, 143, 358, 379
Horberg, Leland, 47-48, 200, 202,
379
Hough, Jack, 50, 55, 202, 364
Howard, John Langley, 8
Howorth, H. H., 241-42
Hoyt, Joel L., 258-59
INDEX OF NAMES
4*3
Hubbert, M. King, 160
Humphreys, W. J., 38, 69, 140,
205-6, 252, 254, 285
Hunt, J. C., 264
Huntington, Ellsworth, 207
Jacobs, Norman A., 8
Jacobsen, Glen, 167
Jaggar, Thomas A., 112-13, 152-53
Jeffreys, Harold, 17, 27, 80, 117,
i33> *63> 178, 181, 186, 188-89,
351* 359» 369
Joly, J., 87, 120
Kalb, Bernhard, 167-68
Kanwisher, John W., 208
Karlstrom, Thor, 307
Kay, Marshall, 7
Kelly, Allan O., 32, 193
Kenison, Frank, 6
Kolbe, 299
Kreichgauer, 392
Kroeber, Alfred Louis, 40-41
Krumbein, W. C., 9, 23, 89, 115,
!3*
Kulp, J. L., 55, 271
Lambert, 30
Lammers, William, 6
Lapina, N. N., 235
Lap worth, 105-6
Lecomte du Noiiy, Pierre, 3i8f
Libby, Willard F., 46
Linehan, Daniel, 52n.
Love, S. G., 258, 259
Low, 203-4
Lull, Richard Swann, 321, 331
Lydekker, Richard, 238-39
Lyell, Charles, 48, 234, 261, 304,
3!3
Lyman, Charles P., 232
Ma, Ting Ying H., 32, 73-77, 19?
McFarlan, E., 218-19
Malaise, Rene*, 285, 299
Mallery, Arlington H., 52n.
Maxwell, James Clerk, 17, 25, 366-
69» 377
Mayo, Charles, 7
Mayor, A. G., 76
Meinesz, see Vening Meinesz
Melton, F. A., 160
Mendes, J. C., 28
Meryman, Harold T., 242-43
Meyer, 195
Millis, John, 271
Moodie, Roy L., 261
Munk, Walter, 33
Nares, G. S., 64
Negris, P., 142-43
Neuville, H., 229-31
Nikiforoff, C. C., 69
Nolke, 138
Nordenskjold, N. A. E., 234
Nordenskjold, N. O. G., 52n., 168-
69
Olivier, Charles P., 1 1
Pauly, Karl A., 32, 70-71, 195
Penck, 196, 281, 282
Perry, Ralph Barton, Jr., 7
Peter the Great, 244
Philipp, 107
Piggett, C. S., 49
Piri Reis, 520.
Pirsson, Louis V., 80, 82
Planck, Max, 365
Poinsot, Louis, 377
Politzer, Mrs. Use, 8, 391
Pollock, James B., 223
Priestly, Raymond E., 52, 60
Punshon, E. R, 389
Ramsay, Wilhelm, 161, 279
Reid, Henry Fielding, 82
Rensch, 336
424
EARTH S SHIFTING CRUST
Revelle, Roger, 33
Richter, C. F., 162-63
Roberts, Leo, 7
Routh, 369
Rowe, Mrs. Stanley, 7
Runcorn, S. K., 250
Saks, N. V., 235
Sanderson, Ivan T., 8, 230, 320
Sarton, George, 7, 21, 392
Sayles, R. W., 223
Scholander, P. F., 208
Schuchert, Charles, 80, 82, 140
Schwarzschild, M., 390
Scott, John, 7
Scott, Robert Falcon, 166-67
Scott, W. B., 64, 227-28
Sears, Paul B., 290
Seward, A. C., 63
Shackleton, Ernest, 59
Shaler, 219
Shapley, Harlow, 6, 17, 35, 368-69
Simpson, George Gaylord, 9, 315,
329> 333~36» 337
Slichter, L. B,, u
Sloss, L. L, 9, 23, 89, 115, 131
Smart, W. M., 117
Smith, Albert C., 138
Smith, Warren D., 223-24
Sonder, 106
Stokes, William Lee, 39-40, 56-
57> IS1
Stubbs, P. H. S., 33
Stutzer, Otto, 311
Suess, Eduard, 314
Suess, H. E., 277, 300
Sukachev, V. N., 246
Sullivan, Eileen, 8
Tatel, H. E., 150
Tazieff, Haroun, 207
Termier, Pierre, 140
Thomas, Charles W., 171
Toll, Baron, 234-35
Tolmachev, I. P., 241-42, 256
Tresca, M., 190
Tuve, M. A, 150
Tyndall, John, 39
Umbgrove, J. H. F., 9, 28, 35, 60,
68, 84-85, 106-8, 120, 125, 129,
133, 138, 141, 142, 148, 156, 173,
223, 332, 35°» 358
Urey, Harold C., 11, 126, 202, 294
Urry, W. D., 49-50, 52, 195, 202,
300, 301, 364
van Camp, Robert, 6
Van Woerkom, A. J., 43
Vening Meinesz, F. A., 28, 87-88,
106-7, !73> *74> 392
Verrill, Mrs, A. Hyatt, 7
Volchok, H. L., 55, 271
Vorse, Mrs. Mary Heaton, 7
Wallace, Alfred Russel, 62-63, 65,
220, 310, 325, 326
Walters, M. L, 52n,
Warrington, Henry, 5-6
Wegener, Alfred von, 26-31, 133,
136, 196, 386, 392
Weller, J. Marvin, 312
Willis, 138
Wilson, J. Howard, 219
Wollin, Goesta, 55
Wright, G. F., 219
Wright, W. B., 44, 52
Tanner, W. F., 198
Zeuner, 281, 282
INDEX OF SUBJECTS
Academy of Sciences (Russian), 8,
244-45
adaptation, 61, 228-32, 250, 322-
23. See also mammoth
adaptive radiation, 32Qff, 333ff
Alaska, earlier location of pole,
2?5» 3°3~8
amateurs, 3, 6
ammonites, 63
amphibians, 62, 63. And see in-
dividual species
ancient maps, showing ice-free
Antarctica, 52n.
"Angaraland," 137
annual rings in fossilized woods,
68-69
anomalies, in Antarctica, 161, 163,
172; in Arabian Sea, 174; in
Cyprus, 173; in East Indies, 173;
in Great Rift Valley of Africa,
173; in Harz Mountains, 173; in
Hawaiian Islands, 172, 174; in
the Himalayas, 173, 176, 384;
in India, 173-76; in Nero Deep,
173; in Scandinavia, 161, 174; in
U.S.A., 174; negative, 162, 173-
75; positive, 175
Antarctica, coal beds in, 59; ero-
sion in, 59; evidence for dis-
placement, 54, 364; forested, 60;
icecap in, larger than Wisconsin
icecap, 38 iff, and see icecap,
displacement, centrifugal effect;
possesses folded mountains, 59;
summer described, i68ff; tem-
perate periods in, 50-55, 58-61,
217, 305; unglaciated, ibid.; see
also Wisconsin glaciation, cores,
ionium method, radioelement
dating, Hudson Bay, displace-
ment; tropical flora in, 60
anomaly, as epeirogenic uplift,
121-22; centrifugal effects of,
179-80, 373-74; from triaxial
deformation, 181-82. See also
uncompensated mass, icecap,
displacement
antelope, 233
anticlines, 88-90
anticyclonic winds, 53, 215
anti-Darwinians, 319
"Appalachia," 141
Archaeocyathidae, 59
Arctic Ocean, only of Mesozoic
age, 149
armadillos, 335
ash trees, 65
asthenosphere, 14, 99-100, 185-92,
353; currents in, alleged cause
of mountain building, 87; fluid-
ity, 186; liquid properties, basic
assumption for displacement
hypothesis, 388; not sharply
demarcated from lithosphere,
i5off, i85ff; solidity of, refuted,
189; strength estimated from
deep-focus earthquakes, 188-89;
viscosity explains delay in iso-
static adjustment, 179, 184; vis-
cosity increased by pressure,
i86ff. See also displacements,
viscosity
asymmetry of icecaps, i, i8ff, Fig.
basalts, 133, 172; found on floor of
Atlantic, 152. And see plateau
basalts
426
EARTH'S SHIFTING CRUST
beaches, on highlands, 224-25; on
inland mountains, 142-43
bears, 262, 335
beaver, giant, 227, 262, 335; small,
262
"bipolar mirrorism," 327-29
birch, 65
bison, 233, 262; giant, 335
"Brady Interval" (retreat of Wis-
consin icecap), 201
bursting stress on crust, 91, 92, 199,
345> 35°* 378> 384J compared
with crushing point of basalt,
350; computed, 361; near criti-
cal point now, 381
calamites, 62
Cambrian, 67
camel, extinct in North America,
2*27; in Pleistocene Alaska, 307-
8, 335» 336
carbon dioxide gas, and Climatic
Optimum, 209; causes general
warming of climate, 208; and
recession of icecap, 209; result-
ing from volcanism, 207-8, 211
Carboniferous, 62, 66, 68, 72
caribou, 262
"Gary Advance" (of Wisconsin ice-
cap), 201, 211, 272
centrifugal effect, i, 2, 158:, 374ff;
calculated, 359-60; distinguished
from Eotvos effect, 357; exist-
ence questioned, 357, 365ff; this
objection answered, 365-78;
mechanism, Ch. XI passim; not
exhausted in local crust defor-
mations, 359; of anomalies, 172;
of icecaps, 16-19, 1 59~^3, 172,
igSff, 340, 356, 384; of triaxial
deformation of earth, 184-85;
still operative, 379-86; sufficient
to fracture crust, 362 (and see
fractures); tangential compo-
nent, 341, Table III, 372. See
also anomaly, displacement,
Eotvos effect, icecap, isostasy,
isostatic adjustment, uncom-
pensated mass
climate, Chs. II, III, VII, VIII, X;
abrupt changes of, 15, 237-43;
various explanations of these re-
futed, 60-61; these changes evi-
dence for displacement, 78; and
only explanation for frozen
mammoths, 244; gradual
changes, 77-78; this theory re-
futed, 78; measured by radio-
element dating of pollen, 29off;
in Siberia, 195, 234; unrelated to
internal heat of earth, 118. See
also cores, displacements, extinc-
tions, ionium method, radioele-
ment dating, volcanism
"Climatic Optimum," 31, 54ff, 196,
201, 209, 255
climatic zones, evidence for dis-
placements, 73; inconstant, 12,
70, and Ch. Ill, passim; mineral
components, 72$
coal beds, 59, 62, 64, 310-11; as
evidence for displacements, 71;
rate of formation, 31 off
"Cochrane Advance" (of Wiscon-
sin icecap), 201, 216; local and
minor, 202
coelacanth, 320
conifers, 65
"contemporaneity" of events with-
in the same geological period,
refuted, 38ff, 4 iff, 44, 45, 65-69,
i28ff, 130, 131
continental drift, 14, 26-31, 75-77,
*33> l83» *96> 372; refuted, 27,
28-30. See also Ma and Wegener
in Index of Names
continental shelf, 141, 142-44
"continental slope," 141
INDEX OF SUBJECTS
427
continents, ancient (Brooks the-
ory), 137; building, related to
volcanic islands and sedimenta-
tion, 115; elevation and subsid-
ence explained, 153-57 (see a^so
sea level, elevation, displace-
ment); invaded by epicontinen-
tal seas, 85, 140; this phenome-
non quasi-periodic, 85; origin of,
hitherto unexplained, 12, iggff;
permanence alleged, 134-35,
298; refuted, 135!!, 139-48, 150^,
157, 298-300; shape correspond-
ence, 28; strength of lithosphere
at ocean bottoms, refuting
"floating continents" idea, 28;
submergence, as evidence for
displacement of crust, 156-57;
sunken, 137-45, 29gff, 326. See
also land bridges
cooling of earth, 82, no; adduced
to explain isostatic anomalies,
182; to explain mountain build-
ing, 79-80; this theory refuted,
87-88; to explain universal tem-
perate climate, 66-67; tn*s t^ie"
ory refuted, 67-69, and Chs. Ill,
VII, IX passirrt
coral, 62, 73^; evidence for dis-
placement, 75-77 (see also Ma
in Index of Names); seasonal
variation in cells, 74; indicators
of latitude, 73-74
cores, 50-51, 54, 55-56, 271, 277,
282, 284-87, 290-303, 305, 309.
See also ionium method, radio-
element dating
crack in earth's crust, world-wide
(Ewing canyons), 81, 109, no,
113, 385; consistent with force
pulling Americas southward,
385; continuous earthquake ac-
tivity along, 109, 385; related to
displacement, past or impend-
ing, no, 385; and volcanism,
i*3
craters, 126
Cretaceous, 63, 68, 72, 75, 131, 309
crinoids, camariate, 334
crust, compression on, 100-2, 153,
1 75-76» 383-84; crushing
strength (compressive strength),
358; elasticity, 92, 101; folding,
80-90; hydrostatic balance, 99-
100; rapid warping, 216, 222—26;
resistance to fracture slight, 351;
sinking under weight of sedi-
ments, refuted, 81-82 (see geo-
synclines); stretching, 91—99,
153; structure, i5off; tensile
strength, 100, 124, 175-76, 186,
200, 357-58, 391; thickness, 14,
123-24; variation in thickness,
124-25, 151-52. See also burst-
ing stress, displacement, frac-
tures, "mountain roots," nega-
tive geography
crustaceans, 73
cycle of climatic change, 21,000
years long, 309
Dawn Redwood, 320
deer, 262, 335
"denudation," area of, 163
"deposition," area of, 163
deserts, in all geological periods,
68; mainly in horse latitudes, 72
Devonian, 62, 66, 68-69, 75> 7§
diastrophisms, diastrophic disturb-
ances, 131, 312. See also dis-
placements, mountain building
diatoms, fresh- water, in mid- At-
lantic, 299; evidence for land
mass in that area, 299ff
dinosaurs, 335; not degenerate,
336; extinction attributed to
displacements, 336
displacements of crust, i, 2, 13-15,
2off,
428
EARTH'S SHIFTING CRUST
displacements of crust (Cont.)
57, 176, 200, 203ff, 207ff,
219, 237, 24gff, 287, 314, 390,
and Chs. IX, XI, XII passim;
approximate equality of extent,
86; basic assumptions of hypoth-
esis, 377, 387!!; cause local in-
creases in crust strength, 176;
discontinuous, 351-52; economic
consequences of theory, 38off;
effects, 95-96, Figs. II, V, VI,
Ch. XII; evidence for, passim;
topics cited in evidence, 387;
evolution and, 322ff, Ch. X pas-
sim; explain acceleration of geo-
logical processes, 49, 309; and
block mountains, no; and
changes in sea level, 120-26, 196,
311-12; and "Climatic Opti-
mum/' 209-10; and climatic
variation, 40, 65, 70, 78, 285,
310, 312; and changes in oxygen
content of atmosphere, 208; and
conflict between Antevs and de
Geer findings, 213; and differ-
ences in extent of European vs.
American glaciations, 213-15;
and difficulties in isostasy the-
ory, 178-79; and distribution of
species, 329, 339; and emptying
of ecological niches, 33 iff; and
epeirogenic uplifts, 121; and
extinctions, 251-56, 332, 334,
336ff, 339; and fracture patterns,
91-110; and gaps in fossil rec-
ord, 338-39; and geographical
isolation of species, 322—24, 339;
and geosynclines, 90; and growth
of continents, 122, i53ff; and
heat of earth, 116-19; and in-
constancy of climatic zones, 70,
303; and inconstancy of icecap
locations, i7iff, 287; and "in-
terstadials," 209-10; and land
bridges, i38ff; and lateral com-
pression of sedimentary rock in
India, 176; and mountain
ranges, i38ff; and rapid crustal
warping, 216; and "sea mounts/'
i47ff; and structure of crust,
152-53; and tempo of evolu-
tion, 322ff, 339; and various
anomalies, 175-76; and Virenz,
332ff, 339; and volcanism, 43,
111-15, 196, 204-8, 269; and
world-wide lowering of tempera-
ture, 43; future, of Antarctic
icecap, 380-86; impending ac-
tivity, evidence for, 382!!; inter-
vals between beginnings of,
about 40,000 years, 277, 284,
38off; intervals variable, 380;
isostasy and, i59ff, 365-78; in
North America, see Wisconsin
glaciation and Ch. VII passim;
northward in Siberia, 271 and
Ch. VIII passim; Pennsylvanian
cycles and, 313; periodicity, 85-
86; perpetual, 304, 314; physical
mechanism, Campbell hypoth-
esis, 388, Ch. XI passim; objec-
tions to this explanation, 22;
answered, i97ff, 352-78; pos-
sibly responsible for all funda-
mental features of crust and
earth's history, 314; prior to
Wisconsin glaciation, Ch. IX
passim; proposed causes, 15, 32,
70; icecap as one of these, 17-
21 and Ch. XI passim; rearward
buildup of ice prolonging ac-
tivity, 353-54, 385~86; sus-
pended if both poles are in
oceans, 354ff; this objection an-
swered, 354-55; throughout
Paleozoic, 313; time element, 97,
128-31, 277, 284, 38off; viscosity
of asthenosphere no great ob-
stacle to, igoff. See also anomaly,
INDEX OF SUBJECTS
429
Antarctica, asthenosphere, burst-
ing stress, climate, earthquakes,
extinctions, fractures, ice ages,
icecaps, isostasy, isostatic adjust-
ment, lowering of temperature,
meridian of maximum thrust,
mountain building and origins,
poles, triaxial deformation, vis-
cosity, volcanism
distribution of species, i35ff, 325-
29, 339; Ch. Ill, passim
domes and basins, no; related to
displacement, no, 120, 184
downward projections of crust,
124-25, 151-52, 190-92
Drayson hypothesis, 43, and see
Drayson in Index of Names
Drosophila, 319
earth, formed as a solid, n; cool-
ing, 66-67 (and see cooling);
heating, n, 116—19 (and see
heat); magnetic field, 33, 308;
molten origin, discredited, 82-
84, 112, 117, 182; triaxial de-
formation of, 180-84. $ee a^so
centrifugal effect, crust, dis-
placements, equatorial bulge,
isostasy, poles
earthquakes, 90—103, 109, 113, 118,
Figs. II-VI, Ch. XI; deep-focus,
and strength of asthenosphere,
188; function, 384; and impend-
ing crust displacement, 382-86;
in Assam, 383-84; in India, 383;
pushed Himalayas up nearly 200
feet farther from isostatic adjust-
ment, 384; this phenomenon un-
explainable save in terms of dis-
placement, 384; major, from
world-wide stress systems, 382;
from icecap thrust, 382; increas-
ing in frequency and violence,
382-85; minor, of local origin,
382; produce heat by friction,
118; and triaxiality of earth,
189. See also crack in earth's
crust, displacements, fractures,
geosynclines
eccentricity of Antarctic icecap,
i8ff, Fig. I, 198; contrasted with
that of Wisconsin icecap, ig8ff
elephants, 229-33, 336> 337
elevations of land, drastic changes
in, 38, 142, 219-21; adduced to
explain climatic change, 60-61;
this theory refuted, 61; related
to displacements, 120-23, 285.
See also epeirogenic uplifts,
mountain building, beaches,
land bridges, displacements
elk, American, 262; Irish, 262;
killed and preserved by same
sort of conditions as held for
mammoth and mastodon, 262
England, separated from Euro-
pean continent within last 7,000
years, 218-19
Eocene, 64, 69, 309, 314
Eotvos effect, 357, 371-75
epeirogenic uplifts, i2off, 128, 153
epicontinental seas, 85ff, 140, 148-
49
equatorial bulge, accounting for
stretching and compression of
crust, goff, 345-5 1, Figs. XIII,
XIV, XV; lying beneath crust,
346; origin, 370; and rotational
stability, 17, 20, 25, 366. See also
fractures, wedge effect
equipotential surface, 370-72, 374,
377; sea level, 372-73. See also
geoid
erosion, 48, 106, 152-53; and for-
mer continents, 141; and iso-
static adjustment, 162, 177;
mountain building, 80-82; and
peneplains, 177-78; and sedi-
mentary rocks, 129
43°
EARTH S SHIFTING CRUST
Everest, Mount, increased height
since 1950, and displacement,
384
evolution, 12, and Ch. X passim;
causes, 3i5ff; and climate, 32off;
and displacements, 322; "ex-
plosive/' see Virenz; and glacial
periods, 321; and macromuta-
tions, 319; and mutation, 316-
18; mystical explanations, 318—
19; "quantum," see Virenz;
selection pressure, 318; unex-
plained, 315; vast stretches of
time required without drastic
climatic change being adduced,
3 i 6— 20
extinctions, 197, 207, 227; Ch.
VIII passim; and impending dis-
placement, 386; hitherto unex-
plained, 228, 315. See also mam-
moth, mastodons
"Farmdale Advance" (of Wiscon-
sin icecap), 200, 273, 307
"Farmdale-Iowan Interstadial,"
200
ferns, 62, 63
floating of bodies from gases pro-
duced in decomposition, 237;
not observed in very cold waters,
237
foraminifera, and sea mounts, 148;
and displacements, 287, 295-96;
in Arctic, 287
fossilization, a rare accident, 68;
not limited to warm-climate
creatures, 68
fossil record, gaps in, 337-39; ex-
plained, 129, 338
foundering of continents, 1395
foxes, 262
fractures of the crust, 81, 91-99,
log-1^ 385» Figs. II-VI; and
displacements, 91-99, 104-10,
177, 204*1, 209, 364, 379, 391;
major, 93, 935, 1135; minor, 93,
115; more ancient systems oblit-
erated by those from most recent
displacements, 108; and moun-
tain building, 91-99; older the-
ories of origin refuted, 106-7;
and wedge effect, 345ff, 351, 363.
See also centrifugal effect, crust,
displacements, equatorial bulge,
magma, mountain building,
mountains
friction, subcrustal, 118; alleged
brake on displacements, 353;
this objection answered, 353
frozen foods, 238-40; related to
mammoth, 24off
fusion of nuclei, 390
genes, 316, 318, 319
"geoid," 158, 179, 182, 183, 375,
377; represented by sea level,
373
geosynclines, 87-90, 100, 115, 127;
supposed origins, 89-90. See also
centrifugal effect, displace-
ments, mountain building
glaciations, European, not con-
temporaneous with North Amer-
ican, 280-83, 292; Ch. IX passim
glaciers, Ch. II passim, 67, 70, 193;
not universally receding, 1 64-65,
167-68. See icecap
Glossopteris, 60
"Gondwanaland," 137
gradualism, 313-14 (see also Lyell
in Index of Names); a habit of
mind (Einstein quotation), 364
gravitational contraction, insuffi-
cient to account for earth's heat,
116
gravitational surface, 372-73, 377
gravity, 37off; accounts for shape
of earth, 158, 370. See also isos-
tasy, isostatic adjustment
INDEX OF SUBJECTS
431
Greenland, amphibians in, 62;
centrifugal effect of icecap, 381;
displacement in near future pos-
sible, 38 iff; formerly unglaci-
ated, 63, 64, 382, Chs. II, III,
IX; ice sheet still growing, 164-
65; in tandem with Antarctic
icecap, 381; isostatic adjustment
of, contradictory findings, 381;
lignite in, 64; previous location
of pole, 288-302 and Ch. IX
passim; this discovery confirmed,
292, 295, 308
hazel, 65
heat, subcrustal, 116-19; evidence
for displacement of crust, 118;
gradient differs in different con-
tinents, 117; rate of dissipation,
117-18
"Heiskanen formula," 174
Himalayas, uncompensated mass
of, 173, 176; raised by Indian
earthquake of 1950, 384; stand
about 864 feet too high, 173
horse, 227, 233, 262, 338; Pleisto-
cene, 227, 335, 336
horseshoe crabs, 320
Hudson Bay, locale of pole during
Wisconsin glaciation, Ch. VII
passim, 272, 274-75, 288, 299,
300, 303
humidity, increased, and growth of
icecaps, 165
ice, accumulation far faster than
isostatic adjustment, 162, 356;
amount roughly constant, 217,
357
ice ages, alleged causes, 42; these
in conflict with laws of physics,
41-42; allegedly world- wide,
$8ff, 328; this theory refuted,
39-44; and "bipolar mirrorism,"
327-29; in Carboniferous, 67; in
Pleistocene, 303, Ch. VII and
IX; in pre-Cambrian, 67; in
tropics, unexplained, 12, 34;
specifications for adequate the-
ory of, 56-57
icebergs, not evidence of decline
in Antarctic icecap, 170-71;
mode of formation, 170
icecap, Antarctic, accounts for
otherwise unexplained Indian
earthquakes, 383-84; and Cuzco
earthquake, 384; and Ewing
canyons, 385; and increased
strain on crust, 384; alleged re-
cession of, i64ff; eccentrically
placed, i8ff, Fig. I; factor in
world climate, 53; growth con-
temporary with recession of Wis-
consin glaciation, 53; isostatic
adjustment of, i5gff; this asser-
tion refuted, 163-64; less ancient
than formerly believed, 50-56,
161; rapid growth of, 164-65,
171-72; uncompensated, i72ff.
See also anomaly, centrifugal
effect, "Climatic Optimum,0
crack in crust (Ewing canyons),
displacements, ice ages, isostasy,
isostatic adjustment, meridian of
maximum thrust, poles
icecap, North American, Ch. VII
passim. See Wisconsin glaciation
icecaps, i6ff, Chs. II, III, VII, VIII,
IX, XI passim; alleged recession
in Antarctica, i64ff;, best ex-
plained by presence of land at a
pole, 56-57; contrasted with
Martian counterpart, 126-27;
eccentricity, i8ff, i93ff; growth
accelerated by world-wide warm
climate, 165; in the Congo, 37;
in Siberia, 255—56; in tropics at
sea level, 38; incredibly rapid
disappearance, 202 (sec also
carbon dioxide); "misplaced,"
43*
EARTH'S SHIFTING CRUST
icecaps (Cont.)
35-37; mode of movement, 263;
pressures exerted by, 35 iff, 358—
59; rapidity of growth, best evi-
dence for centrifugal effect as-
sumption, 200; rate calculation
suggested by Einstein, 391; si-
multaneous growth and disap-
pearance, evidence for displace-
ment of crust, 53; time element,
277, 284; and world climate,
Chs. II, III, VII. See also anom-
aly, centrifugal effect, "Climatic
Optimum," climate, displace-
ments, earthquakes, ice ages, isos-
tasy, isostatic adjustment, me-
ridian of maximum thrust, poles
ice sheets, compared with litho-
sphere, 99; Cordilleran, 308;
destroy evidence of previous
glaciations, 278-79, 305; Euro-
pean, entered Britain from
northwest, 297-99; evidence for
sunken continents, 142, 297-99;
in India, 36ff; this glacier with-
drew recently, 45ff; in Siberia,
255-56; in tropics, 34ff, Ch. II
passim; Keewatin, 272, 308;
Labradorean, 272-73, 308; mean
summer temperature the decid-
ing factor in growth of, 195;
melting, as evidence for dis-
placement of crust, i7iff; not all
receding, 164; Pleistocene, not
yet compensated isostatically,
162; rate of movement far slower
in Antarctica than in Green-
land, 170; still growing in
Greenland, Baffinland, north-
west U.S.A., 164-65. See also
Greenland, isostasy, isostatic ad-
justment, poles
Ichthyosaurus, 63
"Illinoisan" glaciation, evidence
for pole in western Canada, 276
Imperial Academy of Sciences
(Russian), 8, 244-45
impoverishment of island faunas
and floras, explained, 326-27
insolation curve, 307; insufficient
to cause ice age, 43
"International" and "Heiskanen"
formulas for measuring isostatic
adjustment, 174
intrazonal adaptation, 333—35
ionium method, 41, 49-56, 271,
282, 285, 293-94; confirmed, 55;
pronounced reliable by Ein-
stein, 364; sources of error in,
55. See also cores, icecaps, radio-
element dating
"lowan Advance" (of Wisconsin
icecap), 201
iris, 65
isolation, geographic, factor in
evolution, 321, 324
isostasy, 121, 134-35* i58ff; and
centrifugal effect, 365-78; and
conflicting measurements of
gravity data, 381; departures
from, 372ff; established only at
long intervals, 178; theory ques-
tioned, i6off, i72ff, 174, 175, 177,
183, 382; theory stands or falls
with displacement hypothesis,
185; theory threatened by per-
sistence of old anomalies and
triaxial deformation, 182-83,
188-89. $ee anomaly, anomalies
(locations), centrifugal effect,
displacements, isostatic adjust-
ment
isostatic adjustment, 1590% 175,
199, 216-17, 220-21, 251, 356-57,
391; and centrifugal effects,
375ff; and displacements, 178,
198-99, 251, 255; contradictory
INDEX OF SUBJECTS
433
measurements of in Greenland,
381; "exists only in imagina-
tion," 177; extreme slowness of,
161-63; imperfect or lacking in
Antarctica, 159, 160, 161; and
in Scandinavia, 161; ineffective
in counteracting centrifugal ef-
fects of icecaps, 164; measure-
ments highly doubtful, 160; a
rare, exceptional condition, 178;
seemingly lacking under pene-
plains, 177
ivory, 228, 238-39
Jurassic, 63, 66, 72, 107, 131; coal
deposits, 71
Labyrinthodonts, 63
land bridges, 135(1, 139, 285, 297-
300, 305, 325-26; and evolution,
321; explained, 149
Laramide Revolution, 131
lava floods, 111, 126, 204, 207
Lepidodendron, 62
Libocedrus, 65
lignite, in Greenland, 64
lime trees, 65
lithosphere, 27-28, 99-100, 175,
352. See also asthenosphere,
crust, displacements, earth-
quakes, fractures
"living fossils/' 320-21
lowering of temperature, world-
wide, and volcanism, 42-43, 206;
explained by displacement, 43;
will not explain simultaneous
glaciation and deglaciation, 194;
will not explain Wisconsin gla-
ciation, 194-95; wrongly as-
sumed, 38-44
macromutation, 319
magma, 84, 153, 157, 188; and
fractures of crust, 91, 96, Figs.
III-VI, 119-120, 122-123; and
mountain building, 98-100
magnetic field of earth, changes
in, related to displacements, 33,
308
mammoth, 227, 228, 250-51, 256,
258, 261, 335; Beresovka, 8, 244-
49, 250, 253ff; diet included
grasses and buttercups, 243, 246-
47, but no conifers, 248, nor
typical Arctic plants, 246-47;
probable cause of his death,
253-55; stomach contents ana-
lyzed, 245-49; species, edibility,
239-40; frozen, 228, 240-44; in
summer, 243; lacks sebaceous
glands, 229; not adapted to cold,
228-32; probably same species
as Indian elephant, 233; re-
mains allegedly washed to polar
islands by spring floods, 234;
refuted, 235-36; source of ivory,
228; study of skin, compared
with that of Indian elephant,
229; subcutaneous fat layer,
231-33; tusks dredged up from
Arctic Ocean, 251
"Mankato Advance" (of Wiscon-
sin icecap), 201, 211, 288
"Mankato Maximum" (high point
of Mankato Advance phase of
Wisconsin icecap), 201, 202, 212,
213
maps, confirming hypothesis of ice-
free period in Antarctica, 52n.
Mars, 126-27
mastodon, 227, 257-65, 335; diet
included plants common in
present-day New York State,
260, 264-65; survived ice age,
266; found in bogs and swamps,
257-58; stomach contents ana-
lyzed, 257, 264
mathematics, limitation of, 378
434
EARTH'S SHIFTING CRUST
"maturity" of a species. See intra-
zonal adaptation
meridian of maximum thrust
(presently 96° E. Long.), 15,
ign. and Fig. I, 66, 92, 95, 96,
109, 128, 220-21, 356, 383
meridional faults, same as major
fractures. See fractures
meteoric phenomena, explainable
only in terms of planetesimal
hypothesis, 11
meteorological factors of glacia-
tion, 38
Miocene, 65, 235, 314
"missing links," 337-39
moon, mountains on, formed by
collisions, 126; allegedly torn
away from Pacific basin, 183
moose, 262
moraines, 70; evidence for dis-
placement of crust, 70, 288
mountain building and origins,
Campbell hypothesis, 90-103;
chronology examined, 128-31;
explainable by displacements,
85-86, 90; from cracking and
buckling of crust, 80-81; miscel-
laneous explanations, 87; not
exclusively from erosion, 81; not
from cooling of earth, 79-80;
not from shrinking of crust, 83-
84; not simultaneous and world-
wide, 130; on ocean bottoms,
149; related to volcanism, 80,
111-15; source a world-wide
force, 83-84; this force quasi-
periodic, 84-85; nearly contin-
uous, 131; source of energy,
103-4; unexpectedly frequent,
i28ff; unexplained, 79ff, 176. See
also centrifugal effect, crust, dis-
placements, fractures, geosyn-
clines, "sea mounts," volcanism
"mountain roots," 124, 192
mountains, 12, 15, Ch. IV; absent
on Mars, 126-27; aid in distri-
bution of species, 327-29; and
centrifugal effect, 103-4; an<^ geo-
synclinal theory, 89-91; and
magmatic intrusions, 98-100;
different kinds described, 80; in
Antarctica, 59; island chains of,
80, 115-16; source of energy for
folding, 103-4; submerged, 80,
116; volcanic, 80. See also crust,
centrifugal effect, geosynclines,
magma, moon, Paricutin, "sea
mounts," volcanism
mutations, 3i6ff; incapable of pro-
ducing new species, 316-17; ma-
jority harmful or indifferent,
317; and natural selection, 317;
"systematic," 3igff; this theory
adduced to solve problem of
time, 320; discredited, 319
natural selection, 315 (see evolu-
tion); incapable of producing
new species, 316; requires exces-
sively long time, 318
"Nearctis," 137
nebular theory of earth's origin,
10; discredited, 11-12
"negative geography," 124
neo-Darwinians, 316-19
New Siberian Islands, site of mam-
moth remains, 234, of fruit trees,
234-36; forested in Miocene and
Pliocene, 235
niche, life, sgoff; ecological, ibid.;
emptying explained, 331
"North Atlantis," 137, 140
oak, 65
oblateness, and poleward com-
ponent of gravity, 375. See equa-
torial bulge
INDEX OF SUBJECTS
435
ocean basins, origin unexplained,
12, i45ff; alleged permanence,
1506:. See also beaches, conti-
nents (sunken), foundering, os-
cillation of ocean bottoms, sea
bottoms, "sea mounts"
Ohio glaciation, 48, 273; evidence
for displacement, 379-80
Old Red Sandstone formation, a
fossil desert, 68
Oligocene, 107
Ordovician, 75
orogenic uplifts, 120
oscillation, rhythmic, of ocean bot-
toms, 142, 148
oscillation of ice sheets, 48, 57, 165,
204ff. See also volcanic dust,
volcanism
Oxygen- 18 method, 294
Paleocene, 64
palm trees, 320
parallelogram of forces, used in
computing centrifugal effect and
its tangential component, 343-
44
Paricutin, 80; related to present
beginning of displacement, 384
peat bogs, 64
peccaries, 262, 335
peneplains, and isostatic adjust-
ment,
"Pennsylvanian" period (Carbon-
iferous), 312
periodicity, of displacements, 85-
86, 277, 284, 38off; of mountain
building, 84-86; accounted for
by displacements, 85-86
permafrost, 223, 241, 244, 256
Permian, 63, 72, 30
Permo-Carboniferous, 68, 71, 311;
coal deposits, 71
Peter the Great, 244
pines, 65
Piri Reis maps, confirming recent
deglaciation of Antarctica, 52n.
pivot points in a displacement, 15.
See also triaxial deformation of
earth
plane trees, 65
planetesimal hypothesis, 11
planetoids, collision with earth a
possible cause of displacements
of crust, 32
plasticity, of solids under pressure,
190-91
plateau basalts, 119, 153, 188
Pleistocene, 70, 107, 131, 196, 208,
218, 227, 235, 267-68, 277, 309,
335; accepted chronology of gla-
ciations weak, 278-83; ended
catastrophically, 267-69; Euro-
pean glaciations not contempo-
rary with American, *8off; fifth
glaciation identified, 278, 282;
ice sheets not fully compensated
to date, 162
plication, 83, 89
Pliocene, 69, 235, 314
"pluvial" periods, 39
poles, alleged immobility of, as
example of hardening of the
categories, 25, 31, 61, 386; as
example of circular reasoning,
65-66; and gyroscopic effect of
earth's rotation, 24 (see also
equatorial bulge); causes of ap-
parent shift, 24ff (and see dis-
placements); in Alaska, Ch. IX;
in Greenland, Ch. IX passim;
that location accounting for
New York temperate-zone fauna
enclosed in ice sheet, 289;
method for locating earlier posi-
tions, 274ff; position of, 13; posi-
tion after next displacement,
386; shifts a necessary hypoth-
esis, 3off, 386-87; stability of,
436
EARTHS SHIFTING CRUST
poles (Cont.)
Ch. I, 365; wanderings, 32-33.
See also Hudson Bay, icecaps,
Wisconsin glaciation
pollen, agoff
poplar, 65
Pre-Cambrian, 67
precession, 43, and see Drayson in
Index of Names; allegedly re-
lated to 2i,ooo-year climatic
cycle, 310
"predictability," 37Qff; and future
developments, Ch. XII passim;
vindication of displacement hy-
pothesis, 379-80
public interest, necessary for scien-
tific advancement, 3
quick-freezing processes, 238-44
radioactivity, subcrustal, 87, 116;
alleged cause of mountain build-
ing, 87; proposed source of in-
ternal heat of crust, 116-17
radioelement dating, 29, 41, 44-56,
130, 195, 202, 21 off, 307, 309,
374; called reliable by Einstein,
364; questioned because of revo-
lutionary conclusions, 47-48,
212-13, 29off. See also cores,
ionium method; Hough and
Urry in Index of Names
radiolaria, 171; as evidence for in-
creasing coldness of Antarctic
waters, 171
reptiles, along Dvina River, 63;
in Antarctica, 60; in various sub-
Arctic regions, 63
rhinoceros, woolly, 227, 233, 234
Rift Valley (Africa), 81, 143-45,
'73
rifts and rift valleys, 81, 109, no,
113* 385
"Riss" glaciation, evidence for
Eurasian pole, 275
rotational stability, 17, 20, 25, 366-
69
sabertooth cat, 227, 233, 234, 335,
336
San Augustin Plains, 29off
Sangamon Interglacial, 276, 292,
304; contemporary with Wurm
glaciation, 292
scorpions, 320
sea bottoms, contain mountain
ranges, 29, 145!!; contain vol-
canoes, 29; cores taken from,
see cores, ionium method, radio-
element dating; evidence for
sunken continents, 137-45, 2995,
326 (see also land bridges); not
deeply sedimented, 29, 146, 148-
49; not smooth plains, 28-29,
145; recurring uplifts, 142, 148.
See also continents, crust, moun-
tain building, volcanic islands,
volcanism
sea level, as equipotential surface,
371, 373; changes in, 15, 120-26,
134, 196, 216; changes unex-
plained by melting of icecaps,
196, 2i7ff, 220; "eustatic"
change, 272; evidence for fall,
223; fall explained by growing
Antarctic icecap, 221-23, 226;
not universally rising, 222
"sea mounts," i47ff
seasonal changes, 68-69
sedimentary beds of continents,
formed under sea, 140
sedimentary rocks, 59, 78, 129, 310;
95% ground down, 129
sediments, marine, 7 iff, 197, 271,
Ch. XI; extremely slow deposi*
tion rate, 146; and turbidity,
146-47. See also cores, ionium
method, radioelement dating,
sedimentary rocks
INDEX OF SUBJECTS
437
selection pressure, mild, 318;
strong (i.e., major climatic
change), 321
Sequoia, 65
sharks, 320
shrinking of crust, 82-84, 87, no;
refuted, 83-84. See also cooling
"sial" and "sima," 152
Sierra Nevadas, accounted for by
"gridiron" fracture systems, io6
Silurian, 75, 129
simplicity of a theory, 388
sloth, giant, 227
snow, increased fall in Antarctica,
164-65; rapid accumulation in
Antarctica, i67ff; explained, 169
solids, behavior of, at extremely
high pressures, 189; relationship
to deep-focus earthquakes, 189
species, adaptation to different cli-
mates, 61, 322-23; "degenera-
tion" concept refuted, 334-37;
drastic climatic change and,
322-24; extinctions, 197, 207,
227; history compared with in-
dividual growth and aging,
333-37> this notion likened to
medieval scholastic logic, 333;
"maturity," see intrazonal adap-
tation; mutations and, 316-18;
new, not produced, 3i6£f; tropi-
cal, survival refutes theory of
simultaneous world-wide glacia-
tions, 328; "youth," see adap-
tive radiation. See also adapta-
tion, climate, distribution,
extinction, ice ages, land
bridges, mammoth, mastodon,
volcanism
sphenodon, 320
Spitzbergen, formerly warm, 62-65
stabilizing effect of equatorial
bulge, 17, 20, 25
vstorms, 236, 254-55, 266-71
strandlines, 224ff
stratigraphy handicapped by ero-
sion, 129
subcrustal currents, 87-88; lack of
evidence for, 88
sunspot cycles, 165
surface of mass, 372-73, 377
swamp-cypress, 65
"Swedish Time Scale," 211. See
varves
"sweepstakes" process in distribu-
tion of species, 326
synclines, 90* See also geosynclines
Taxodium, 65
"Tazewell Advance" (of Wiscon-
sin icecap), 200-1, 218
"Tazewell Maximum," 211
Teleosaurus, 63
tempo, of evolution, Ch. X; of
geological change, 12. See also
displacements, icecaps, moun-
tain building
"Tethys Sea," 137, 140
thermal energy arriving at surface,
66
tigers, 230; their thick fur not an
adaptation to cold, 232
tree ferns, in Antarctica, 60
Triassic, 63, 130; coal deposits, 71
triaxial deformation of earth, 180-
84; amount of equatorial oval-
ness, 181; evidence for displace-
ment, 183-84; irreconcilable
with isostasy theory, 183
trilobites, 67
"Two Creeks Interstadial," 201
Tyrannosaurus rex, 320
uncompensated mass, 341, 373-77.
See also anomaly
uniformitarianism, 48, 304, and see
Lyell in Index of Names
universal temperate climates, re-
futed, 65-70
438
EARTH'S SHIFTING CRUST
varves, 68, 211, 309; imply seasonal
changes, 68
Viking settlements, 164; over-
whelmed by growing ice sheets,
165
Virenz, Virenzperiod, 329-31;
coincide with periods of drastic
geological change, 33 iff; follow
creation of empty niches by ex-
tinctions, 337
viscosity of asthenosphere, 14, 86,
179, 184, i86ff; decreased by
heat, 187; increased by pressure,
i86ff. See also asthenosphere,
displacements
"vital force" in species, a piece of
scholastic logic, 333; discredited,
334~37
volcanic dust, relationship to cli-
mate, 2O5ff, 211
volcanic glass shards, found in At-
lantic cores, 294, 296
volcanic islands, location ex-
plained, 115
volcanic zones, distribution unex-
plained, 111-12; related to frac-
ture systems, 113-14
volcanism, 12, 42-43, 97, 304, 312;
and carbon dioxide gas, 207-8;
and Ewing canyons, 113; and
extinctions, 207, 268-70, 304-5;
and fracture systems, 113; and
immense increase of precipita-
tion, 253, 264; and impending
displacement, 386; and moun-
tains, 80, 111-15; and storms,
268-71; and toxic gases, 269;
and Wisconsin glaciation, 196,
200, 204-10; and world-wide
lowering of temperature, 205-
6, 252, 270; cause of readvance
of icecap, 205-6, 252; not merely
local phenomenon, 112-13; the-
ories of origin, 112-14; unre-
lated to alleged molten origin
of earth, 112. See also climate,
crack in earth's crust, displace-
ments, extinctions, magma, Pari-
cutfn
walnut, 65
warm-climate life in polar zones,
f2, 25, 58-65, and Ch. Ill pas-
sim
warming of climate, world-wide,
refuted, 164-65. See also climate
and Chs. II, HI passim
water, volume approximately con-
stant over geological time, 156-
57; as evidence for crust dis-
placement, 156-57
water lilies, in Greenland, 65; in
Grinnell Land, 64, 65; in Spitz-
bergen, 64
wedge effect, 345-51; and equato-
rial bulge, Figs. XIV, XV, 348ff,
36off; and fractures, 345; multi-
plies centrifugal thrust by 500,
349
whale, 337
Wisconsin glaciation, 45, 48, 54,
Ch. VII, 257, 266, 268, 277, 278,
283ff, 287ff, 289, 302, 307, 309,
352, 379» 382; oscillations of, 48,
ig6ff, 281. See also volcanism
wobble, in earth's rotation, 16-17,
32. See also Blanchard and
Gold in Index of Names
wolves, 245, 335
wool, 229-30
world-wide system of submarine
rifts, 81, 109, no, 113, 385
"youth" of a species. See adaptive
radiation
zones. See climatic zones
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